tetrad vs quaternity

tetrad and quaternity both are nouns.

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

As nouns, tetrad and quaternity are synonyms defined as:

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

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

tetrad (noun)	quaternity (noun)
the cardinal number that is the sum of three and one	the cardinal number that is the sum of three and one