| ̷ ̷ ̷ ̷ at hydro- +...- noun
Etymology: hydrocyanic International Scientific Vocabulary hydr- + cyanic
: a very weak poisonous liquid acid HCN or HNC that is formed by solution of hydrogen cyanide in water, is readily made by the action of an acid on a cyanide, and is used chiefly in fumigating against insects, rats, mice and in organic synthesis — called also prussic acid