/ Dictionary / Index T thi-: Meaning and Definition of Find definitions for: thi- Pronunciation: [key] var. ofbefore a vowel: thiazine. T.H.I. Pronunciation: [key] temperature-humidity index. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. they've thiacetic acid 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