ternion vs threesome

ternion and threesome both are nouns.

Word	Noun	Adjective	Verb	Adverb
ternion	Yes	No	No	No
threesome	Yes	No	No	No

As nouns, ternion and threesome are synonyms defined as:

ternion and threesome: the cardinal number that is the sum of one and one and one

Other synonyms of ternion include 3, deuce-ace, III, leash, tercet, ternary, terzetto, three, tierce, trey, triad, trine, trinity, trio, triplet, troika.

ternion (noun)	threesome (noun)
the cardinal number that is the sum of one and one and one	three people considered as a unit
	the cardinal number that is the sum of one and one and one