tetrad vs quatern

tetrad and quatern both are nouns.

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

As nouns, tetrad and quatern are synonyms defined as:

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

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

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