/ Dictionary / Index T Thetis: Meaning and Definition of Find definitions for: The•tis Pronunciation: (thē'tis), [key] — n. Class. Myth. a Nereid, the wife of Peleus and the mother of Achilles. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: thetis (Thesaurus) thetic theurgy Related Content Daily Word Quiz: frugal Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language