tetrad vs quartet

tetrad and quartet both are nouns.

Word	Noun	Adjective	Verb	Adverb
tetrad	Yes	No	No	No
quartet	Yes	No	No	No

As nouns, tetrad and quartet are synonyms defined as:

tetrad and quartet: the cardinal number that is the sum of three and one

Other synonyms of tetrad include 4, four, foursome, IV, Little Joe, quadruplet, quatern, quaternary, quaternion, quaternity.

tetrad (noun)	quartet (noun)
the cardinal number that is the sum of three and one	a musical composition for four performers
	four people considered as a unit
	a set of four similar things considered as a unit
	four performers or singers who perform together
	the cardinal number that is the sum of three and one