an extremely poisonous salt of hydrocyanic acid
"The forensic expert confirmed that the victim died from ingesting a lethal dose of cyanide, an extremely poisonous salt of hydrocyanic acid."
Any compound containing the -C≡N radical or the C≡N^(−1) anion.
"The lab technician carefully disposed of the organic waste, knowing that even trace amounts of cyanide in the solvent posed a severe toxicity risk due to its stable carbon-nitrogen triple bond structure."
To treat or poison with cyanide.
"The gardener accidentally treated his roses with a pesticide that contains cyanide, and now they are slowly dying."