quaternity vs quadruplet

quaternity and quadruplet both are nouns.

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

As nouns, quaternity and quadruplet are synonyms defined as:

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

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

quaternity (noun)	quadruplet (noun)
the cardinal number that is the sum of three and one	a set of four similar things 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