/ Dictionary / Index R regulant: Meaning and Definition of Find definitions for: reg•u•lant Pronunciation: (reg'yu-lunt), [key] — n. a substance, as a chemical, used to control or regulate: herbicides and fungicides as regulants for plant growth. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. regulable regular Related Content Daily Word Quiz: hedonist Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language