The Koine Bible

Greek Lexicon

Rahlfs Septuagint lexicon

ναι

Each form is parsed from its actual Septuagint occurrence; a form may have more than one analysis depending on context.

Greek form	Grammar and occurrences
Ναϊ	noun, accusative, singular, masculine (N.ASM) — Judg.1.31

The same normalized Greek lemma occurs in the SBL Greek New Testament: ναί.

Compare the biblical entry for ναι with classical and later Greek dictionaries collected by Logeion.