Kai (conjunction)
Kai is a word that is a conjunction meaning "and" in Ancient Greek (καί, kaí, [kǎi̯]), Modern Greek (και, kai, [ce]), Coptic (ⲕⲁⲓ, kai, [cɛ]) and Esperanto (kaj, [kai̯]).
Kai is the most frequent word in any Greek text, and thus used by statisticians to assess authorship of ancient manuscripts based on the number of times it is used.