Editing Interlingue (section)

==Linguistic features==
=== Orthography ===
Interlingue is written with 26 Latin letters: [[a]], [[b]], [[c]], [[d]], [[e]], [[f]], [[g]], [[h]], [[i]], [[j]], [[k]], [[l]], [[m]], [[n]], [[o]], [[p]], [[q]], [[r]], [[s]], [[t]], [[u]], [[v]], [[w]], [[x]], [[y]], and [[z]]. The names of the letters are ''a, be, ce, de, e, ef, ge, ha, i, jot, ka, el, em, en, o, pe, qu, er, es, te, u, ve, duplic ve, ix, ypsilon'', and ''zet''.<ref name="pbgrammar">[http://interlingue.pbworks.com/w/page/4887780/Grammatica%20de%20Interlingue%20%28English%29#alfabet Grammatica de Interlingue in English] {{Webarchive|url=https://web.archive.org/web/20131102212130/http://interlingue.pbworks.com/w/page/4887780/Grammatica%20de%20Interlingue%20%28English%29#alfabet|date=2 November 2013}}, F. Haas 1956. Read 31 October 2013.</ref> Accents are written on the five vowels to indicate irregular stress, with the acute accent (á é í ó ú) preferred, but others (è, ê, etc.) permitted.<ref name="pbgrammar" />

===Phonology===
==== Vowels ====
Sources on the pronunciations of the vowels are contradictory. Some say that the vowels have their Continental values (that is, [a e i o u]), others that they have different qualities when long and short; they also differ on the number of diphthongs (e.g. ''au eu ay ey''). Earlier texts on Occidental described seven vowels (the five continental vowels plus y like {{IPAblink|y}}, namely French ''u'' or German ''ü'', and ''eu'' as German ''ö''),<ref>{{Cite web|url=https://occidental-lang.com/resources/cursberger.pdf|title=Occidental Course in 10 Lessons (English translation)}}</ref><ref>[https://occidental-lang.com/resources/LOccidental_-_Langue_dintercomprehension_immediate.pdf L'OCCIDENTAL: Langue d'intercompréhension immédiate] (1928)</ref><ref>{{Cite web |title=ÖNB-ANNO – Kosmoglott (Serie A) |url=https://anno.onb.ac.at/cgi-content/anno-plus?aid=e0g&datum=1929&page=156&size=45 |access-date=27 December 2021 |website=anno.onb.ac.at}}</ref> but by the 1940s the official recommendation was that vocalic ''y'' be pronounced like ''i'' and eu as a diphthong instead of ''ö''.<ref>{{Cite web |title=ÖNB-ANNO – Cosmoglotta (Serie B) |url=https://anno.onb.ac.at/cgi-content/anno-plus?aid=e0m&datum=1945&page=50&size=45 |access-date=27 December 2021 |website=anno.onb.ac.at}}</ref><ref name="pbgrammar" /> Rough English equivalents for the vowels are as follows:<ref name="pbgrammar" /><ref>{{Cite web|url=https://occidental-lang.com/resources/cursberger.pdf|title=Curs de Occidental (Interlingue) – Ric Berger}}</ref><ref name="pbbasis">[http://interlingue.pbworks.com/w/page/4888206/The%20Basis%20of%20International%20Language The Basis of International language] {{Webarchive|url=https://web.archive.org/web/20131103203743/http://interlingue.pbworks.com/w/page/4888206/The%20Basis%20of%20International%20Language|date=3 November 2013}}. Read 1 November 2013.</ref>

* '''a''' as in French, German, Spanish or Italian, or English f'''a'''ther.
* '''e''' open or closed, as German, Spanish or Italian, or English b'''e'''d and y'''e'''s.
* '''i''' as French, German, Spanish and Italian, or English mach'''i'''ne.
* '''o''' open or closed as in French, German, Spanish and Italian, or English d'''oo'''r, h'''o'''t.
* '''u''' as in German, Spanish and Italian, or English r'''u'''le, p'''u'''ll. '''U''' after q is a short, almost consonantal (w).
* '''y''' is a consonant after a vowel or beginning a word before a vowel, otherwise is pronounced as '''i'''.

Interlingue has non-obligatory vowel length. Rough English equivalents of the sounds are as follows:<ref name=":18">{{Cite web |title=Pronunciation – Interlingue for Beginners |url=https://occidental-lang.com/interlingue-for-beginners/1.html |access-date=25 December 2021 |website=occidental-lang.com}}</ref>

*short '''a''' is /æ/ as in "pat"
*short e is /ɛ/ as in "pet"
*short '''i''' is /ɪ/ as in "pit"
*short '''o''' is /ɒ/ as in "pot"
*short '''u''' is /ʊ/ as in "put"

Vowels are short in the following cases:<ref name="pbgrammar" />

# Vowels are short in unstressed syllables (Accented vowels tend to be long: e in {{lang|ie|id'''é'''}}, o in {{lang|ie|son'''o'''ri}}, a in {{lang|ie|dram'''a'''tic}})
# Vowels are short  when followed by two consonants (unless the second consonant is ''r'' or ''l'', a preceding stressed vowel is long)<ref>{{Cite web |title=Pronunciation – Interlingue for Beginners |url=https://occidental-lang.com/interlingue-for-beginners/1.html#6 |url-status=live |archive-url=https://web.archive.org/web/20210709184647/https://occidental-lang.com/interlingue-for-beginners/1.html#6 |archive-date=9 July 2021 |access-date=6 July 2021 |website=occidental-lang.com}}</ref>
# Vowels before a final ''c'', ''ch'' or ''x''
# Vowels in short grammatical particles tend to be short

Examples of long vowels: {{lang|ie|pur}}, {{lang|ie|robe}}, {{lang|ie|blu}}, {{lang|ie|fibre}}, {{lang|ie|table}}.<ref name=":18" />

Examples of short vowels: {{lang|ie|calm}}, {{lang|ie|old}}, {{lang|ie|potte}}, {{lang|ie|flagga}}, {{lang|ie|mann}}, {{lang|ie|fox}}, {{lang|ie|storc}}, {{lang|ie|in}}, {{lang|ie|it}}.<ref name=":18" />

==== Consonants ====
{| class="wikitable" style="text-align: center;"
! colspan="2" rowspan="2" |
! rowspan="2" scope="col" |[[Labial consonant|Labial]]
! colspan="2" scope="col" |[[Alveolar consonant|Alveolar]]
! rowspan="2" scope="col" |[[Postalveolar consonant|Post-alveolar]]
! rowspan="2" scope="col" |[[Palatal consonant|Palatal]]
! rowspan="2" scope="col" |[[Velar consonant|Velar]]
! rowspan="2" scope="col" |[[Glottal consonant|Glottal]]
|-
!{{Small|plain}}
!{{Small|sib.}}
|-
! colspan="2" scope="row" |[[Nasal consonant|Nasal]]
|{{IPA link|m}}
|{{IPA link|n}}
|
|
|
|{{IPA link|ŋ}}
|
|-
! rowspan="2" scope="row" |[[Plosive]]/<br />[[affricate]]
! scope="row" |{{small|[[Fortis and lenis|fortis]]}}
|{{IPA link|p}}
|{{IPA link|t}}
|{{IPA link|t͡s}}
|
|
|{{IPA link|k}}
|
|-
! scope="row" |{{small|[[Fortis and lenis|lenis]]}}
|{{IPA link|b}}
|{{IPA link|d}}
|{{IPA link|d͡z}}
|
|
|{{IPA link|ɡ}}
|
|-
! rowspan="2" scope="row" |[[Fricative]]
! scope="row" |{{small|fortis}}
|{{IPA link|f}}
|
|{{IPA link|s}}
|{{IPA link|ʃ}}
|
|
| rowspan="2" scope="row" |{{IPA link|h}}
|-
! scope="row" |{{small|lenis}}
|{{IPA link|v}}
|
|{{IPA link|z}}
|{{IPA link|ʒ}}
|
|
|-
! colspan="2" scope="row" |[[Approximant]]
|
|{{IPA link|l}}
|
|{{IPA link|ɹ|r}}
|{{IPA link|j}}
|{{IPA link|w}}
|
|}
The consonants are pronounced as in English, with the following exceptions:<ref name="pbbasis" />
*'''c''' when before e and i = {{IPA|ie|ts|label=}}: {{lang|ie|cive}}, {{lang|ie|helice}}, and otherwise as {{IPA|ie|k|label=}}
*'''g''' when before e and i = {{IPA|ie|ʒ|label=}}, French j, or English s in pleasure: {{lang|ie|plage}}, {{lang|ie|giraffe}}; but elsewhere c and g are hard as in can, go
*'''ss''' = {{IPA|ie|s|label=}} as in {{lang|ie|pass}}
*'''s''' between vowels = {{IPA|ie|z|label=}}: {{lang|ie|rose}}, {{lang|ie|positiv}}
*'''z''' = {{IPA|ie|dz|label=}}
*'''zz''' = {{IPA|ie|ts|label=}}
*'''ch''' = {{IPA|ie|ʃ|label=}}, English sh: {{lang|ie|chambre}}
*'''j''' = {{IPA|ie|ʒ|label=}}, French j, or English s in pleasure
*'''t''' as {{IPA|ie|t|label=}}, except when followed by ia, io, iu, or ie and not preceded by an s. Thus the t in {{lang|ie|nation}} is pronounced {{IPA|ie|ts|label=}} but in {{lang|ie|bastion}} as {{IPA|ie|t|label=}}.

Other doubled consonants are pronounced as a single consonant, unless when separated they would be pronounced differently. Ex. {{lang|ie|grammatica}} is pronounced as if written {{lang|ie|gramatica}}, but {{lang|ie|acceptar}} and {{lang|ie|suggestion}} are pronounced as if written as '''ac''' followed by '''ceptar''', and '''sug''' followed by '''gestion'''.<ref name="pbgrammar" />

===Stress===

Words are generally stressed on the vowel before the final consonant:<ref>{{Cite web |title=Cosmoglotta A, 1929, p. 165 |url=http://anno.onb.ac.at/cgi-content/anno-plus?aid=e0g&datum=1929&page=169&size=45 |url-status=live |archive-url=https://web.archive.org/web/20210415020104/https://anno.onb.ac.at/cgi-content/anno-plus?aid=e0g&datum=1929&page=169&size=45 |archive-date=15 April 2021 |access-date=19 October 2020}}</ref> intercal'''ar''', par'''ol''', '''for'''me. Pluralizing a noun does not change the stress: par'''ol'''es, '''for'''mes. The endings '''-bil''', '''-ic''', '''-im''', '''-ul''' and '''-um''' do not change the stress (even when more than one is present in a single word), nor does the adverbial ending -men: ra'''pid'''men, '''dup'''lic, bon'''iss'''im, '''sin'''gul, poss'''i'''bil, '''max'''imum, sta'''tis'''ticas. Two vowels together are diphthongized and do not count as two syllables for the purpose of stress: fa'''mil'''ie, po'''ten'''tie, unless the word is a single consonant or consonant cluster followed by two vowels: d'''i'''e, d'''e'''o. Compound words are stressed based on the last word in the compound: hod'''i'''e, substr'''a'''e. In cases where the accent is irregular, it is indicated by an accent: caf'''é''', '''í'''npossibil, numer'''ó''', n'''ú'''mere, felicit'''á'''.<ref name="pbgrammar" /> The accent mark may also be used for emphasis as needed: '''Yó ea con la (ne tú)'''.<ref name="pbgrammar" />

=== Grammar ===
{{Main|Interlingue grammar}}

==== Articles ====
Like English, Interlingue has [[Article (grammar)#Definite article|definite]] and an [[Article (grammar)#Indefinite article|indefinite articles]]. The definite article (the) is ''li'', and the indefinite (a, an) is ''un''. Plural of a [[noun]] is made by adding ''-s'' after a vowel, or ''-es'' after most consonants.<ref name="pbbasis" /> To avoid pronunciation and stress changes, words ending in -c, -g, and -m only add an -s: un libre, du libre'''s''', li tric, li tric'''s''', li plug, li plug'''s''', li album, pluri album'''s'''.<ref name="pbgrammar" />

The ending of the definite article can be modified to '''lo''' (masculine), '''la''' (feminine), '''lu''' (neuter), '''lis''' (plural), '''los''' (masculine plural), e '''las''' (feminine plural).<ref>{{Cite web|title=Cosmoglotta A, 1927, p. 96|url=https://anno.onb.ac.at/cgi-content/anno-plus?aid=e0g&datum=1927&page=104&size=45|access-date=23 December 2020|archive-date=13 April 2021|archive-url=https://web.archive.org/web/20210413203559/https://anno.onb.ac.at/cgi-content/anno-plus?aid=e0g&datum=1927&page=104&size=45|url-status=live}}</ref> The article itself can also be pluralized before words that are difficult to pluralize on their own: '''lis s''' (the s's).<ref name="pbgrammar" />

==== Personal pronouns ====
Interlingue has two forms for the personal pronouns: one for the subject form ([[nominative]]), and one for the object form ([[accusative]] or [[dative]], i.e. the oblique form):<ref name="pbgrammar" />

{| class="wikitable"
|+
!
!
! colspan="2" |first
! colspan="2" |second
! colspan="2" |third 
(neutral)
! colspan="2" |third
(fem.)
! colspan="2" |third
(masculine)
|-
!
!
!ie
!en
!ie
!en
!ie
!en
!ie
!en
!ie
!en
|-
| rowspan="3" |'''Singular'''
|'''Subject'''
|yo
|I
|tu
|thou
|it
|it
|ella
|she
|il
|he
|-
|'''Object'''
|me
|me
|te
|thee
|it
|it
|la
|her
|le
|him
|-
|'''Possessive'''
|mi
|my
|tui
|thy
|su
|its
|su
|her
|su
|his
|-
| rowspan="3" |'''Plural'''
|'''Subject'''
|noi
|we
|vu
|you
|ili
|they
|ellas
|they
|illos
|they
|-
|'''Object'''
|nos
|us
|vos
|you
|les
|them
|las
|them
|los
|them
|-
|'''Possessive'''
|nor
|our
|vor
|your
|lor
|their
|lor
|their
|lor
|their
|}
The formal second person is ''vu'',<ref name=pbgrammar /> which is also the second person plural. The indefinite personal pronoun "one" is ''on''.<ref name=pbbasis /> One can also specify the gender of third person plural by using ''illos'' (masculine) or e''llas'' (feminine).<ref name=pbgrammar />

==== Grammatical endings ====
Only a few parts of speech in Interlingue (such as verbs in the infinitive) have entirely obligatory endings, while many other endings are optional though sometimes recommended.<ref name=":12">{{Cite web|title=Cosmoglotta B, 1947, p. 27|url=https://anno.onb.ac.at/cgi-content/anno-plus?aid=e0m&datum=1947&page=25&size=45|url-status=live|archive-url=https://web.archive.org/web/20210413203602/https://anno.onb.ac.at/cgi-content/anno-plus?aid=e0m&datum=1947&page=25&size=45|archive-date=13 April 2021|access-date=23 December 2020}}</ref> Some grammatical endings are:

*'''ar, er, ir''': verb infinitive. f'''ar''' (to do), poss'''er''' (be able), scr'''ir''' (to write)
*'''e''': the general substantival (noun) ending. Used obligatorily to differentiate nouns from other parts or speech, for reasons of pronunciation, or optionally for euphony.<ref name="pbgrammar" />
*'''i''': the general adjectival ending, similar to -e in usage.
*'''a''': nouns that end in '''e''' formed from an '''-ar''' verb are often written with the '''-a''' ending if one wishes to emphasize the verbal (active) aspect. The '''a''' ending also makes nouns feminine: angles'''e''' (English person), angles'''o''' (Englishman), angles'''a''' (English woman). This does not apply to nouns that on their own indicate the gender (patre, matre).<ref name=":13">{{Cite web|title=Grammatica de Interlingue in Interlingue|url=http://www.panix.com/~bartlett/Haas.html|url-status=live|archive-url=https://web.archive.org/web/20210211155128/http://www.panix.com/~bartlett/Haas.html|archive-date=11 February 2021|access-date=18 August 2020}}</ref>
*'''o''': indicates the masculine gender in the same way '''a''' indicates the feminine.<ref name="pbgrammar" />

==== Correlatives ====
While correlatives were not made to match a pre-determined scheme (such as the correlatives in Esperanto<ref>{{Cite web|title=Wikibooks: Esperanto/Appendix/Table of correlatives|url=https://en.wikibooks.org/w/index.php?title=Esperanto/Appendix/Table_of_correlatives&oldid=3241754|access-date=22 September 2021|archive-date=13 April 2021|archive-url=https://web.archive.org/web/20210413203401/https://en.wikibooks.org/w/index.php?title=Esperanto%2FAppendix%2FTable_of_correlatives&oldid=3241754|url-status=live}}</ref>), the majority match the prefixes and suffixes in the chart below.<br />
{| class="wikitable"
!
!QU- 
(interrogative/relative)
!T- 
(demonstrative)
!ALQU- 
(undefined)
!NEQU- 
(negative)
!-CUNC 
(indeterminate)
!'''Ø'''
(collective)
|-
| -I 
(persons,

standard demonstrative)
|qui 
(who)
|ti 
(this/that)
|alqui 
(someone)
|nequi 
(nobody)
|quicunc 
(whoever)
|omni 
(every)
|-
| -O 
(things)
|quo 
(what)
|to 
(that)
|alquo 
(something)
|nequo 
(nothing)
|quocunc 
(whatever)
|omno 
(all)
|-
| -EL 
(both persons and things)
|quel 
(which)
|tel 
(such)
|alquel 
(any)
|nequel
|quelcunc 
(whichever)
|chascun
(each)
|-
| -AL 
(quality)
|qual 
(which, what a)
|tal 
(that)
|alqual 
(any kind)
|nequal
|qualcunc
|
|-
| -AM 
(way, mode)
|quam 
(as)
|tam 
(so)
|alquam 
(anyhow)
|nequam
|quamcunc 
(however)
|
|-
| -ANT 
(quantity)
|quant 
(how many)
|tant 
(so much)
|alquant 
(somewhat)
|nequant
|quantcunc
|
|-
| -ANDE 
(time)
|quande 
(when)
|tande 
(then)
|alquande
|nequande 
(never)
|quandecunc
|sempre 
(always)
|-
| -U 
(place)
|u 
(where)
|ci / ta 
(here / there)
|alcu 
(somewhere)
|necu 
(nowhere)
|ucunc 
(anywhere)
|partú 
(everywhere)
|}
Notes on the correlatives:<ref>{{Cite web|title=Occidental Course in 10 Lessons|url=https://occidental-lang.com/resources/OccidentalCourseIn10Lessons-EnglishTranslation.pdf|access-date=10 March 2020|archive-date=24 October 2020|archive-url=https://web.archive.org/web/20201024091247/https://occidental-lang.com/resources/OccidentalCourseIn10Lessons-EnglishTranslation.pdf|url-status=live}}</ref>

'''Alcun''' (some) and '''necun''' (no, none) are respectively the adjectives of '''alquel''' and '''nequel.'''

The -'''al''' series is adverbialized with the -men ending: '''qualmen''' (how) '''talmen''' (that way).

Correlatives can take the plural ending: '''queles''', '''quales, tis, omnis''', etc.

'''Ci''' (here) and '''ta''' (there) can be affixed to '''ti''' and '''to''' to indicate proximity or distance: '''ti libre''' (this book), '''ti-ci''' libre (this book here), '''ti-ta''' libre (that book there), '''tis''' (these), '''tis-ci''' (these here), '''tis-ta''' (those there), '''to-ci''' (this here), '''to-ta''' (that there).

Many derivatives are formed from the correlatives: '''qualitá''' from '''qual''' + '''itá''', '''quantitá''' from '''quant''' + -'''itá''', '''omnipotent''' from '''omni + potent.'''

==== Verbs ====
Verbs in Interlingue have three endings: -'''ar''', -'''er''', and -'''ir'''. Conjugation is performed with a combination of endings and auxiliary verbs. The verb {{lang|ie|esser}} (to be) is exceptional in being written {{lang|ie|es}} in the present  tense, while the {{lang|ie|esse}} form is the imperative.<ref name=":13" />
{| class="wikitable"
|+
Simple Verb Tenses
!
!Form
!Interlingue
!English
!Notes
|-
|[[Infinitive]]
| -ar / -er / -ir
|{{lang|ie|amar}} / {{lang|ie|decider}} / {{lang|ie|scrir}}
|to love / to decide / to write
|
|-
|[[Present tense|Present]]
| -a / -e / -i
|{{lang|ie|yo ama}} / {{lang|ie|decide}} / {{lang|ie|scri}}
|I love / decide / write
|
|-
|[[Past tense|Past]]
| -t
|{{lang|ie|yo amat}} / {{lang|ie|decidet}} / {{lang|ie|scrit}}
|I loved / decided / wrote
|stress thus falls on the last syllable: {{lang|ie|yo am'''at'''}}
|-
|[[Future tense|Future]]
|{{lang|ie|va}} + {{gcl|INF}}
|{{lang|ie|yo va amar}} / {{lang|ie|decider}} / {{lang|ie|scrir}}
|I will love / decide / write
|{{lang|ie|va}} on its own is not a verb (to go = {{lang|ie|ear}} or {{lang|ie|vader}})
|-
|[[Conditional mood|Conditional]]
|{{lang|ie|vell}} + {{gcl|INF}}
|{{lang|ie|yo vell amar}} / {{lang|ie|decider}} / {{lang|ie|scrir}}
|I would love / decide / write
|Also used for hearsay: {{lang|ie|Un acusation secun quel il vell...}} {{Translation|An accusation alleging him to have...}} {{lit|an accusation according to which he would have...}}
|-
|[[Imperative mood|Imperative]]
| -a! / -e! / -i!
|{{lang|ie|ama!}} / {{lang|ie|decide!}} / {{lang|ie|scri!}}
|love! / decide! / write!
|Imperative of {{lang|ie|esser}} is {{lang|ie|esse}}.
|}

{| class="wikitable"
|+
Compound Verb Tenses
!
!Form
!Interlingue
!English
!Notes
|-
|[[Present perfect|Perfect]]
|{{lang|ie|ha}} + -t
|{{lang|ie|yo ha amat}}
|I have loved
|{{lang|ie|ha}} on its own is not a verb (to have = {{lang|ie|haver}})
|-
|[[Pluperfect]]
|{{lang|ie|hat}} + -t
|{{lang|ie|yo hat amat}}
|I had loved
|
|-
|[[Future perfect]]
|{{lang|ie|va har}} + -t
|{{lang|ie|yo va har amat}}{{lang|ie|
|I will have loved
|
|-
|[[Conditional perfect|Perfect conditional]]
|{{lang|ie|vell har}} + -t
|{{lang|ie|yo vell har amat}}
|I would have loved
|
|-
|[[Future in the past]]
|{{lang|ie|vat}} + {{gcl|INF}}
|{{lang|ie|yo vat amar}}
|I was going to love
|
|-
|[[Irrealis mood|Precative]]
|{{lang|ie|ples}} + {{gcl|INF}}
|{{lang|ie|ples amar!}}
|please love!
|
|-
|[[Hortative]]
|{{lang|ie|lass}} + {{gcl|INF}}
|{{lang|ie|lass nos amar!}}
|let us love!
|
|-
|[[Optative mood|Optative]]
|{{lang|ie|mey}} + {{gcl|INF}}
|{{lang|ie|yo mey amar}}
|may I love
|Same as English {{lang|en|may}} in the optative mood 
(as in {{lang|en|May the Force be with you}}).
|-
|[[Participle#Forms|Present participle]]
| -nt
|{{lang|ie|amant}}
|loving
| -ir verbs become -ient
|-
|[[Gerund]] (adverbial participle)
| -nte
|{{lang|ie|amante}}
|(while) loving
| -ir verbs become -iente
|}

The present participle is used to qualify nouns: {{lang|ie|un cat ama}} ({{Translation|a cat loves}}), {{lang|ie|un amant cat}} ({{Translation|a loving cat}}) and is often seen in adjectives such as {{lang|ie|fatigant}} (tiring, from {{lang|ie|fatigar}}, to tire). The gerund is used to indicate another action or state of being going on at the same time: {{lang|ie|scriente un missage, yo videt que...}} ({{Translation|writing a message, I saw that...}}).<ref>{{Cite web|title=Cosmoglotta A, 1938, p. 69|url=https://anno.onb.ac.at/cgi-content/anno-plus?aid=e0g&datum=1938&size=45&page=70|access-date=9 January 2022|website=anno.onb.ac.at}}</ref>

==== Adverbs ====
Interlingue has '''primary adverbs''' and '''derived adverbs'''. Primary adverbs are not generated from other parts of speech and are thus not formed using any special endings: ''tre'' (very), ''sempre'' (always), etc.<ref name="pbgrammar" />

Derived adverbs are formed by adding the suffix -'''men''' to an adjective ('''rapid''' = quick, '''rapidmen''' = quickly) Adjectives may be used as adverbs when the sense is clear:<ref name="pbgrammar" /><ref>{{Cite web|title=Cosmoglotta A, 1927, p. 50|url=https://anno.onb.ac.at/cgi-content/anno-plus?aid=e0g&datum=1927&page=56&size=45|url-status=live|archive-url=https://web.archive.org/web/20210413203519/https://anno.onb.ac.at/cgi-content/anno-plus?aid=e0g&datum=1927&page=56&size=45|archive-date=13 April 2021|access-date=6 March 2021}}</ref>

'''Il ha bon laborat''' = He has worked well ("He has worked good")

'''Noi serchat long''' = We looked for a long time ("We searched long")

==== Derivation ====
[[File:Occidental derivation.png|thumb|An example of derivation from the magazine Cosmoglotta.]]
[[File:De_Wahl's_Rule.png|thumb|Flowchart demonstrating derivation of nouns from verbs using de Wahl's rule.]]
The application of [[de Wahl's rule]] to verbs, and the usage of numerous suffixes and prefixes, was created to resolve irregularities that had plagued creators of language projects before Occidental, who were forced to make the choice between regularity and unnatural forms, or irregularity and natural forms. The prevailing view before its application was that natural forms needed to be sacrificed for the sake of regularity, while those that opted for naturalism were forced to admit numerous irregularities when doing so ([[Idiom Neutral]] for example had a list of 81 verbs with special radicals<ref>{{Cite web|url=http://anno.onb.ac.at/cgi-content/anno-plus?aid=e0m&datum=1948&size=45&page=45|title=Cosmoglotta B, 1948, p. 45|access-date=20 January 2019|archive-date=15 April 2021|archive-url=https://web.archive.org/web/20210415020143/https://anno.onb.ac.at/cgi-content/anno-plus?aid=e0m&datum=1948&size=45&page=45|url-status=live}}</ref> used when forming derivatives), a paradox summed up by [[Louis Couturat]] in 1903 as follows:<ref>{{Cite book|url=https://archive.org/details/histoiredelalang00coutuoft/page/472/mode/2up|title=Histoire de la langue universelle|last1=Couturat|first1=Louis|last2=Leau|first2=Léopold|date=1903|publisher=Paris Hachette|others=Robarts – University of Toronto|quote=Translation: "En somme, on se trouvait acculé à cette antinomie : les mots internationaux ne sont pas réguliers, et les mots réguliers ne sont pas internationaux; l'opinion dominante était qu'il fallait sacrifier la régularité à l'internationalité dans la formation des mots. Julius Lott concluait qu'on ne peut pas éviter les irrégularités des langues naturelles, et VON Wahl, qu'on ne peut pas donner à la L. I. plus de simplicité et de régularité que n'en comportent nos langues."}}</ref>

<blockquote>In short, one finds oneself confronted by the antinomy that the words that are international are not regular, and the words that are regular are not international; the prevailing opinion [of naturalists such as Julius Lott and de Wahl] was that regularity should be sacrificed for internationality in the formation of words.</blockquote>

The rules created by de Wahl to resolve this were first described in 1909<ref>{{Cite web|url=https://sites.google.com/site/latinosineflexio/-1909-13-discussiones-api#1909:21|title=Abstracti Verbal-Substantives – Edgar de Wahl (Discussiones de Academia pro Interlingua, Nov. 1909: 21–5)|access-date=19 December 2020|archive-date=18 August 2016|archive-url=https://web.archive.org/web/20160818041229/https://sites.google.com/site/latinosineflexio/-1909-13-discussiones-api#1909:21|url-status=live}}</ref> in the ''Discussiones'' of Peano's Academia pro Interlingua and are as follows:

#If, after the removal of '''-r''' or '''-er''' of the infinitive, the root ends in a vowel, the final -t is added. Crear (to create), crea/t-, crea/t/or, crea/t/ion, crea/t/iv, crea/t/ura.
#If the root ends in consonants d or r, they are changed into s: decid/er (to decide), deci/s-, deci/s/ion deci/s/iv. Adherer (to adhere), adhe/s-, adhe/s/ion
#In all other cases, with six exceptions, the removal of the ending gives the exact root: duct/er, duct-, duct/ion.

Once these rules were applied, Occidental was left with six exceptions. They are:<ref>{{Cite web|url=https://anno.onb.ac.at/cgi-content/anno-plus?aid=e0g&datum=1929&page=197&size=45|title=Cosmoglotta A, 1929, p. 193|access-date=6 March 2021|archive-date=13 April 2021|archive-url=https://web.archive.org/web/20210413203409/https://anno.onb.ac.at/cgi-content/anno-plus?aid=e0g&datum=1929&page=197&size=45|url-status=live}}</ref>

#ced/er, cess- (concession)
#sed/er, sess- (session)
#mov/er, mot- (motion)
#ten/er, tent- (temptation)
#vert/er, vers- (version)
#veni/r, vent- (advent)

Suffixes are added either to the verbal root or the present theme of the verb (the infinitive minus -r). An example of the latter is the suffix -ment: move/r, move/ment (not movetment), experi/r, experi/ment (not experitment), and -ntie (English -nce): tolera/r (tolerate), tolera/ntie, existe/r (exist), existe/ntie.<ref>{{Cite web|url=https://anno.onb.ac.at/cgi-content/anno-plus?aid=e0g&datum=1929&page=197&size=45|title=Cosmoglotta A, 1929, p. 192|access-date=6 March 2021|archive-date=13 April 2021|archive-url=https://web.archive.org/web/20210413203409/https://anno.onb.ac.at/cgi-content/anno-plus?aid=e0g&datum=1929&page=197&size=45|url-status=live}}</ref>

==== Affixes ====
The major prefixes and suffixes used in word derivation in Interlingue are added to either the present theme (infinitive minus -r), verbal root (infinitive minus two preceding vowels), or perfect theme (present theme + t or +s for verbs finishing with -d or -r) of verbs, as well as other types of speech. Some of the affixes used are:<ref name=":13" />

{| class="wikitable"
|+
!affix
!meaning
!before affix
!after affix
|-
| -abil/-ibil
|able
|posser (to be able)
|possibil (possible)
|-
| -ada/-ida
| -ade
|promenar (to stroll)
|promenada (a walk, a promenade)
|-
| -ar
|general verb
|sicc (dry)
|siccar (to dry)
|-
|bel-
|kinship by marriage
|fratre (brother)
|belfratre (brother-in-law)
|-
|des-
|cessation
|infectar (infect)
|desinfectar (disinfect)
|-
|dis-
|separation, dispersion
|membre (member)
|dismembrar (dismember)
|-
| -er-
|doer of verb
|lavar (wash)
|lavere / lavera / lavero (washer)
|-
| -ette
|diminutive
|dom (house)
|domette (cottage)
|-
|ex-
|ex-
|presidente (president)
|ex-presidente (ex-president)
|-
|ho-
|this
|semane (week)
|ho-semane (this week)
|-
|ín-
|in-, un-, etc.
|credibil (believable)
|íncredibil (unbelievable)
|-
| -ion
| -ion
|crear (create)
|creation (creation)
|-
| -iv
| -ive
|exploder (explode)
|explosiv (explosive)
|-
| -ment
| -ment
|experir (to experience)
|experiment (experiment)
|-
|mi-
|half
|fratre (brother)
|mifratre (half-brother)
|-
|mis-
|false (mis-)
|comprender (understand)
|miscomprender (misunderstand)
|-
|non-
|non-
|fumator (smoker)
|nonfumator (non-smoker)
|-
| -ntie
| -nce
|tolerar (tolerate)
|tolerantie (tolerance)
|-
| -or
| -er, -or
|distribuer (distribute)
|distributor (distributor)
|-
| -ori
| -ory
|currer (run)
|cursori (cursory)
|-
|per-
|through, all the way
|forar (pierce)
|perforar (perforate)
|-
|pre-
|before
|historie (history)
|prehistorie (prehistory)
|-
|pro-
|to the front
|ducter (lead)
|producter (produce)
|-
|re-
|re-
|venir (come)
|revenir (return)
|-
|step-
|step-
|matre (mother)
|stepmatre (stepmother)
|-
| -ura
| -ure
|scrir (write)
|scritura (scripture)
|}