Full Definition of FACET. 1. : a small plane surface (as on a cut gem) â see brilliant illustration. 2. : any of the definable aspects that make up a subject (as of contemplation) or an object (as of consideration). 3. : the external corneal surface of an ommatidium.
Definition of cyanide. 1  1 : a compound of cyanogen with a more electropositive element or group: such asa : potassium cyanideb : sodium cyanide. 2  2 : cyanogen 1.
The cyanide ion is isoelectronic with carbon monoxide and with molecular nitrogen. Most cyanides are highly toxic. Organic cyanides are usually called nitriles; in these, the CN group is linked by a covalent bond to a carbon-containing group, such as methyl (CH 3) in methyl cyanide (acetonitrile).