half a dozen vs sestet

half a dozen and sestet both are nouns.

Word	Noun	Adjective	Verb	Adverb
half a dozen	Yes	No	No	No
sestet	Yes	No	No	No

As nouns, half a dozen and sestet are synonyms defined as:

half a dozen and sestet: the cardinal number that is the sum of five and one

Other synonyms of half a dozen include 6, Captain Hicks, hexad, sextet, sextuplet, sise, six, sixer, VI.

half a dozen (noun)	sestet (noun)
the cardinal number that is the sum of five and one	a musical composition written for six performers
	a rhythmic group of six lines of verse
	a set of six similar things considered as a unit
	six performers or singers who perform together
	the cardinal number that is the sum of five and one