Editing Part of speech (section)

==Open and closed classes==
{{See also|Function word|Content word}}

Word classes may be either open or closed. An ''open class'' is one that commonly accepts the addition of new words, while a ''closed class'' is one to which new items are very rarely added. Open classes normally contain large numbers of words, while closed classes are much smaller. Typical open classes found in English and many other languages are [[noun]]s, [[verb]]s (excluding [[auxiliary verbs]], if these are regarded as a separate class), [[adjective]]s, [[adverb]]s and [[interjection]]s. [[Ideophone]]s are often an open class, though less familiar to English speakers,<ref name="guide99">''The Art of Grammar: A Practical Guide,'' Alexandra Y. Aikhenvald, [https://books.google.com/books?id=XFBVBQAAQBAJ&pg=PA99 p. 99]</ref><ref>G. Tucker Childs, "African ideophones", in ''Sound Symbolism,''  [https://books.google.com/books?id=Uov84NavOR8C&pg=PA179 p. 179]</ref>{{efn|name=ideophones|1=Ideophones do not always form a single grammatical word class, and their classification varies between languages, sometimes being split across other word classes. Rather, they are a phonosemantic word class, based on derivation, but may be considered part of the category of "expressives",<ref name="guide99"/> which thus often form an open class due to the productivity of ideophones. Further, "[i]n the vast majority of cases, however, ideophones perform an adverbial function and are closely linked with verbs."<ref>G. Tucker Childs, "African ideophones", in ''Sound Symbolism,''  [https://books.google.com/books?id=Uov84NavOR8C&pg=PA181 p. 181]</ref>}} and are often open to [[nonce word]]s. Typical closed classes are [[preposition]]s (or postpositions), [[determiner]]s, [[grammatical conjunction|conjunction]]s, and [[pronoun]]s.<ref>{{cite web|url=http://strazny.com/encyclopedia/sample-function-words.html|title=Sample Entry: Function Words / Encyclopedia of Linguistics|access-date=2014-12-21|archive-date=2018-08-30|archive-url=https://web.archive.org/web/20180830211625/http://www.strazny.com/encyclopedia/sample-function-words.html|url-status=live}}</ref>

The open–closed distinction is related to the distinction between [[syntactic category|lexical and functional categories]], and to that between [[content word]]s and [[function word]]s, and some authors consider these identical, but the connection is not strict. Open classes are generally lexical categories in the stricter sense, containing words with greater semantic content,<ref name="Lexical and Functional categories">{{cite book|last=Carnie|first=Andrew|title=Syntax: A Generative Introduction|year=2012|publisher=Wiley-Blackwell|location=New Jersey|isbn=978-0-470-65531-3|pages=51–52}}</ref> while closed classes are normally functional categories, consisting of words that perform essentially grammatical functions. This is not universal: in many languages verbs and adjectives<ref>{{Cite journal| doi = 10.1075/sl.1.1.04dix| title = Where Have all the Adjectives Gone?| journal = Studies in Language| volume = 1| pages = 19–80| year = 1977| last = Dixon | first = Robert M. W. | author-link = Robert M. W. Dixon}}</ref><ref name="dixon2006">''Adjective classes: a cross-linguistic typology,'' [[Robert M. W. Dixon]], Alexandra Y. Aikhenvald, OUP Oxford, 2006</ref><ref name="guide97">''The Art of Grammar: A Practical Guide,'' Alexandra Y. Aikhenvald, [https://books.google.com/books?id=XFBVBQAAQBAJ&pg=PA96 p. 97]</ref> are closed classes, usually consisting of few members, and in Japanese the formation of new pronouns from existing nouns is relatively common, though to what extent these form a distinct word class is debated.

Words are added to open classes through such processes as [[Compound (linguistics)|compounding]], [[Morphological derivation|derivation]], [[Coining (linguistics)|coining]], and [[Borrowing (linguistics)|borrowing]]. When a new word is added through some such process, it can subsequently be used grammatically in sentences in the same ways as other words in its class.<ref>{{cite book|last=Hoff|first=Erika|title=Language Development|year=2014|publisher=Cengage Learning|location=Belmont, CA|isbn=978-1-133-93909-2|page=171}}</ref> A closed class may obtain new items through these same processes, but such changes are much rarer and take much more time. A closed class is normally seen as part of the core language and is not expected to change. In English, for example, new nouns, verbs, etc. are being added to the language constantly (including by the common process of [[verbing]] and other types of [[conversion (word formation)|conversion]], where an existing word comes to be used in a different part of speech). However, it is very unusual for a new pronoun, for example, to become accepted in the language, even in cases where there may be felt to be a need for one, as in the case of [[Gender-neutral pronoun#English|gender-neutral pronouns]].

The open or closed status of word classes varies between languages, even assuming that corresponding word classes exist. Most conspicuously, in many languages verbs and adjectives form closed classes of content words. An extreme example is found in [[Jingulu language|Jingulu]], which has only three verbs, while even the modern Indo-European [[Persian language|Persian]] has no more than a few hundred simple verbs, a great deal of which are archaic. (Some twenty Persian verbs are used as [[light verb]]s to form compounds; this lack of lexical verbs is shared with other Iranian languages.) Japanese is similar, having few lexical verbs.<ref>''Categorial Features: A Generative Theory of Word Class Categories,'' {{cite book| url = https://books.google.com/books?id=QoNIBQAAQBAJ&pg=PT54| title = p. 54| isbn = 9781316194638| last1 = Panagiotidis| first1 = Phoevos| date = 4 December 2014| publisher = Cambridge University Press}}</ref>{{Failed verification|date=April 2025}} [[Basque verbs]] are also a closed class, with the vast majority of verbal senses instead expressed periphrastically.

In [[Japanese language|Japanese]], verbs and adjectives are closed classes,{{sfn|Dixon|1977|p=48}} though these are quite large, with about 700 adjectives,<ref>''The Typology of Adjectival Predication,'' Harrie Wetzer, [https://books.google.com/books?id=ORUUwhdDPpUC&pg=PA311 p. 311]</ref><ref name="guide96">''The Art of Grammar: A Practical Guide,'' Alexandra Y. Aikhenvald, [https://books.google.com/books?id=XFBVBQAAQBAJ&pg=PA96 p. 96]</ref> and verbs have opened slightly in recent years. [[Japanese adjectives]] are closely related to verbs (they can predicate a sentence, for instance). New verbal meanings are nearly always expressed periphrastically by appending {{Nihongo||する|suru|to do}} to a noun, as in {{Nihongo||運動する|undō suru|to (do) exercise}}, and new adjectival meanings are nearly always expressed by [[adjectival noun (Japanese)|adjectival noun]]s, using the suffix {{Nihongo||〜な|-na}} when an adjectival noun modifies a noun phrase, as in {{Nihongo||変なおじさん|hen-na ojisan|strange {{not a typo|man}}<!-- do NOT translate this a "uncle" -->}}. The closedness of verbs has weakened in recent years, and in a few cases new verbs are created by appending {{Nihongo||〜る|-ru}} to a noun or using it to replace the end of a word. This is mostly in casual speech for borrowed words, with the most well-established example being {{Nihongo||サボる|sabo-ru|cut class; play hooky}}, from {{Nihongo||サボタージュ|sabotāju|sabotage}}.<ref>{{cite web |url=http://japaneselevelup.com/homage-to-%E3%82%8Bru-the-magical-verbifier/ |title=Homage to る(ru), The Magical Verbifier |date=2011-07-18 |author=Adam |access-date=2015-02-22 |archive-date=2021-01-15 |archive-url=https://web.archive.org/web/20210115210949/https://japaneselevelup.com/homage-to-%E3%82%8Bru-the-magical-verbifier/ |url-status=live }}</ref> This recent innovation aside, the huge contribution of [[Sino-Japanese vocabulary]] was almost entirely borrowed as nouns (often verbal nouns or adjectival nouns). Other languages where adjectives are closed class include Swahili,<ref name="guide97"/> [[Bemba language|Bemba]], and [[Luganda]].

By contrast, [[Japanese pronouns]] are an open class and nouns become used as pronouns with some frequency; a recent example is {{Nihongo||自分|jibun|self}}, now used by some as a first-person pronoun. The status of Japanese pronouns as a distinct class is disputed, however, with some considering it only a use of nouns, not a distinct class. The case is similar in languages of Southeast Asia, including Thai and Lao, in which, like Japanese, pronouns and terms of address vary significantly based on relative social standing and respect.<ref name="guide98">''The Art of Grammar: A Practical Guide,'' Alexandra Y. Aikhenvald, [https://books.google.com/books?id=XFBVBQAAQBAJ&pg=PA98 p. 98]</ref>

Some word classes are universally closed, however, including demonstratives and interrogative words.<ref name="guide98"/>