Meaning of -ETH in English

I. verb suffix

or -th

Etymology: Middle English, from Old English -eth, -ath, -th; akin to Old High German -it, -ōt, -ēt, 3d singular ending, Latin -t, -it

— used to form the archaic third person singular present of verbs

do th

II. adjective suffix

— see -th II

Merriam-Webster's Collegiate English vocabulary.      Энциклопедический словарь английского языка Merriam Webster.