-eth

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
Example: doth II. adjective suffix — see -th II

Merriam-Webster's Collegiate Dictionary