/ Dictionary / Index C cardio-: Meaning and Definition of Find definitions for: cardio- Pronunciation: [key] a combining form meaning “heart,” used in the formation of compound words: cardiogram. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. carding machine cardioaccelerator Related Content Daily Word Quiz: tactful Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language