quadruplet vs quadruple

quadruplet and quadruple both are nouns.

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

As nouns, quadruplet and quadruple are synonyms defined as:

quadruplet and quadruple: a set of four similar things considered as a unit

Other synonyms of quadruplet include quartet, quartette.

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

quadruplet (adjective)	quadruple (adjective)
	four times as great or many
	having four units or components

quadruplet (verb)	quadruple (verb)
	increase fourfold