/ Dictionary / Index H heterocyst: Meaning and Definition of Find definitions for: het•er•o•cyst Pronunciation: (het'ur-u-sist"), [key] — n. Bacteriol. one of the enlarged nitrogen-fixing cells occurring along the filaments in some blue-green algae. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. heterocyclic heterodactylous Related Content Daily Word Quiz: simian Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language