/ Dictionary / Index H heterosis: Meaning and Definition of Find definitions for: het•er•o•sis Pronunciation: (het"u-rō'sis), [key] — n. Genetics. the increase in growth, size, fecundity, function, yield, or other characters in hybrids over those of the parents. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: heterosis (Thesaurus) heterosexuality heterosporous Related Content Daily Word Quiz: mamba Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language