half a dozen vs hexad

half a dozen and hexad both are nouns.

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

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

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

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

half a dozen (noun)	hexad (noun)
the cardinal number that is the sum of five and one	the cardinal number that is the sum of five and one