In chemistry, a cyanide (from Greek kyanos 'dark blue') is a chemical compound that contains a C≡N functional group.  The cyanide ion CN− is one of the most poisonous chemicals. It may cause death in minutes.

Cyanides are produced by certain bacteria, fungi, and algae. It is an antifeedant in a number of plants. Cyanides are found in substantial amounts in certain seeds and fruit stones, e.g., those of bitter almonds, apricots, apples, and peaches.