potassium cyanide vs cyanide

potassium cyanide and cyanide both are nouns.

Word	Noun	Adjective	Verb	Adverb
potassium cyanide	Yes	No	No	No
cyanide	Yes	No	No	No

As nouns, cyanide is a hypernym of potassium cyanide; that is, cyanide is a word with a broader meaning than potassium cyanide:

potassium cyanide: a poisonous salt (KCN) used in electroplating and in photography
cyanide: an extremely poisonous salt of hydrocyanic acid

potassium cyanide (noun)	cyanide (noun)
a poisonous salt (KCN) used in electroplating and in photography	an extremely poisonous salt of hydrocyanic acid
	any of a class of organic compounds containing the cyano radical -CN