tierce vs threesome

tierce and threesome both are nouns.

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

As nouns, tierce and threesome are synonyms defined as:

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

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

tierce (noun)	threesome (noun)
one of three equal parts of a divisible whole	three people considered as a unit
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.