quaternion vs quatern

quaternion and quatern both are nouns.

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

As nouns, quaternion and quatern are synonyms defined as:

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

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

quaternion (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