Reconstruction:Proto-Finnic/-ta

• *-da (with even-syllable vowel stems)
• *-tä, *-dä (front vowel harmony)

From Proto-Uralic *-ta (ablative ending).

*-ta / *-tä

1. Partitive ending.

As per usual rules (of 'suffixal gradation'), the consonant *-t- undergoes lenition to *-d- when preceded by an unstressed syllable, but this is prevented if preceded by a consonant (e.g. *-ct- instead of **-cd- in partitive forms of nominals with *-inën, stem *-ic(c)e-).

• Estonian: -d, -a
• Finnish: -ta, -a
• Ingrian: -ta, -a
• Karelian:
  • North Karelian: -ta, -a
  • South Karelian: -ta, -a
• Livonian: -tā, -dā, -ța, -ta, -da, -tõ, -dõ, -õ
• Livvi: -du, -tu, -u
• Ludian: -d, -t
• Veps: -d, -t
• Võro: -d, -t
• Votic: -ta, -a

From Proto-Uralic *-ta(t).

*-ta / *-tä

1. The second-person plural personal ending for verbs.

• Attached after a tense or mood marker. In the present indicative, this was *-k-; this led to gemination in practically all descendants (*-ktV > *-ttV), which was then widely extended by analogy to other tenses and moods as well.^[1]
  • As per usual rules (of 'suffixal gradation'), the consonant *-t- undergoes lenition to *-d- when preceded by an unstressed syllable, but any consonant immediately preceding it - e.g. the indicative present marker - will prevent this (*-kt- instead of **-kd-).
• The final vowel was probably originally *-a/*-ä, and influenced in many descendants by the second-person plural personal pronoun *tek/*töö.^[1]

• Estonian: -te
• Finnish: -tte (vowel influenced by te), (dialectal) -tta (Ostrobothnia, Lapland, Karelia), -ja (South Ostrobothnia, past; < *-i-da)
• Ingrian: -tta
• Karelian:
  • North Karelian: -tta (present/past), -(i)ja (past; < *-i-da)
  • South Karelian: -tta
• Livonian: -tõ, -t
• Livvi: -tto
• Ludian: -tte
• Veps: -t
• Votic: -tta/-ttõ
• Võro: -t, -q