threesome vs tierce

threesome and tierce both are nouns.

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

As nouns, threesome and tierce are synonyms defined as:

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

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

threesome (noun)	tierce (noun)
three people considered as a unit	one of three equal parts of a divisible whole
the cardinal number that is the sum of one and one and one	the cardinal number that is the sum of one and one and one
	the third canonical hour; about 9 a.m.