/ Dictionary / Index T thermo-: Meaning and Definition of Find definitions for: thermo- Pronunciation: [key] a combining form meaning “heat,” “hot,” used in the formation of compound words: thermoplastic. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. thermite thermoacidophile Related Content Daily Word Quiz: leonine Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language