Editing Old Latin (section)

=== Vowels ===
[[Image:Old latin diphthongs nochar.svg|200px|thumb|Diphthong changes from Old Latin (left) to Classical Latin (right){{sfn|Allen|1897|p=6}}]]

{|
|- style="vertical-align: top;"
|
{| class="wikitable" style="text-align: center"
|+Monopthongs
!
![[Front vowel|Front]]
![[Central vowel|Central]]
![[Back vowel|Back]]
|-
![[Close vowel|Close]]
|{{IPA link|i}} ⟨[[I]]⟩
|({{IPA link|ɨ}} ⟨[[I]]⟩ ~ {{IPA link|ʉ}} ⟨[[U|V]]⟩)
|{{IPA link|u}} ⟨[[U|V]]⟩
|-
![[Close-mid vowel|Close-mid]]
|{{IPA link|e}} ⟨[[E]]⟩
|
|{{IPA link|o}} ⟨[[O]]⟩
|-
![[Open vowel|Open]]
|
|{{IPA link|ä}} ⟨[[A]]⟩
|
|}
|
{| class="wikitable" style="text-align: center"
|+Diphthongs
! colspan="2" rowspan="2" |
! colspan="2" |Endpoint
|-
!{{Small|{{IPA|/i̯/}}}} ⟨-I⟩
!{{Small|{{IPA|/u̯/}}}} ⟨-V⟩
|-
! rowspan="8" |Start point
!{{Small|{{IPA|/ä/}}}} ⟨A-⟩
|{{IPA|äi̯}} ⟨AI⟩
|{{IPA|äu̯}} ⟨AV⟩
|-
!{{Small|{{IPA|/e/}}}} ⟨E-⟩
|{{IPA|ei̯}} ⟨EI⟩
|{{IPA|eu̯}} ⟨EV⟩
|-
!{{Small|{{IPA|/o/}}}} ⟨O-⟩
|{{IPA|oi̯}} ⟨OI⟩
|{{IPA|ou̯}} ⟨OV⟩
|}
|}

Most original PIE ([[Proto-Indo-European language|Proto-Indo-European]]) diphthongs were preserved in stressed syllables, including {{IPA|/ai/}} (later ''ae''); {{IPA|/ei/}} (later ''ī''); {{IPA|/oi/}} (later ''ū'', or sometimes ''oe''); {{IPA|/ou/}} (from PIE {{IPA|/eu/}} and {{IPA|/ou/}}; later ''ū'').

The Old Latin diphthong ''ei'' evolves in stages: ''ei'' > ''ẹ̄'' > ''ī''. The intermediate sound ''ẹ̄'' was simply written ''e'' but must have been distinct from the normal long vowel ''ē'' because ''ẹ̄'' subsequently merged with ''ī'' while ''ē'' did not. It is generally thought that ''ẹ̄'' was a higher sound than ''e'' (e.g. perhaps {{IPA|[eː]}} vs. {{IPA|[ɛː]}} during the time when both sounds existed). Even after the original vowel {{IPA|/ei/}} had merged with ''ī'', the old spelling ''ei'' continued to be used for a while, with the result that ''ei'' came to stand for ''ī'' and began to be used in the spelling of original occurrences of ''ī'' that did not evolve from ''ei'' (e.g. in the genitive singular ''-ī'', which is always spelled ''-i'' in the oldest inscriptions but later on can be spelled either ''-i'' or ''-ei'').

In unstressed syllables, *oi and *ai had already merged into ''ei'' by historic times (except for one possible occurrence of ''poploe'' for ''populī'' "people" in a late manuscript of one of the early songs). This eventually also evolved to ''ī''.

Old Latin often had different short vowels from Classical Latin, reflecting sound changes that had not yet taken place. For example, the very early [[Duenos inscription]] has the form ''duenos'' "good", later found as ''duonos'' and still later ''bonus''. A countervailing change ''wo'' > ''we'' occurred around 150 BC in certain contexts, and many earlier forms are found (e.g. earlier ''votō, voster, vorsus'' vs. later ''vetō, vester, versus'').

Old Latin frequently preserves original PIE thematic case endings ''[[#Second declension .28o.29|-os]]'' and ''[[#Second declension .28o.29|-om]]'' (later ''-us'' and ''-um'').