/ Dictionary / Index T thorac-: Meaning and Definition of Find definitions for: thorac- Pronunciation: [key] var. ofbefore a vowel: thoracic. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Thor thoracentesis Related Content Daily Word Quiz: digression Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language