IV vs foursome

IV and foursome both are nouns.

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

As nouns, IV and foursome are synonyms defined as:

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

IV (noun)	foursome (noun)
administration of nutrients through a vein	four people considered as a unit
the cardinal number that is the sum of three and one	the cardinal number that is the sum of three and one