septet vs sevensome

septet and sevensome both are nouns.

Word	Noun	Adjective	Verb	Adverb
septet	Yes	No	No	No
sevensome	Yes	No	No	No

As nouns, septet and sevensome are synonyms defined as:

Other synonyms of septet include septette.

septet (noun)	sevensome (noun)
a musical composition written for seven performers	seven people considered as a unit
seven people considered as a unit
a set of seven similar things considered as a unit
seven performers or singers who perform together
the cardinal number that is the sum of six and one