Meaning

noun a branch of the Tai languages

originFrom Middle English tho, tha, from Old English þā (“the, those”, plural), from Proto-West Germanic *þai, from Proto-Germanic *þai (“those”), from Proto-Indo-European *to-, *só (“that”). Cognate with Saterland Frisian do (“the”, plural). Doublet of they.

Etymology from Wiktionary, CC BY-SA 3.0