/ Dictionary / Index H hydrocyanic acid: Meaning and Definition of Find definitions for: hy'drocyan'ic ac'id Pronunciation: [key] a colorless, highly poisonous liquid, HCN, an aqueous solution of hydrogen cyanide. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. hydrocyanic hydrodesulfurization Related Content Daily Word Quiz: soporific Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language