hydrogen cyanide

WordReference Random House Unabridged Dictionary of American English © 2025

hy′drogen cy′anide, 

1. Chemistry a colorless poisonous gas, HCN, having a bitter almondlike odor: in aqueous solution it forms hydrocyanic acid.

• 1880–85

Collins Concise English Dictionary © HarperCollins Publishers::

hydrogen cyanide noun

1. a colourless poisonous liquid with a faint odour of bitter almonds, usually made by a catalysed reaction between ammonia, oxygen, and methane. It forms prussic acid in aqueous solution and is used for making plastics and dyes and as a war gas. Formula: HCN
   Also called: hydrocyanic acid