quaternion vs quadruplet

quaternion and quadruplet both are nouns.

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

As nouns, quaternion and quadruplet are synonyms defined as:

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

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

quaternion (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