quadruplet vs foursome

quadruplet and foursome both are nouns.

Word	Noun	Adjective	Verb	Adverb
quadruplet	Yes	No	No	No
foursome	Yes	No	No	No

As nouns, quadruplet and foursome are synonyms defined as:

quadruplet and foursome: the cardinal number that is the sum of three and one

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

quadruplet (noun)	foursome (noun)
a set of four similar things considered as a unit	four people considered as a unit
one of four children born at the same time from the same pregnancy	the cardinal number that is the sum of three and one
the cardinal number that is the sum of three and one