half-dozen vs half dozen

half-dozen and half dozen both are adjectives.

Word	Noun	Adjective	Verb	Adverb
half-dozen	No	Yes	No	No
half dozen	No	Yes	No	No

As adjectives, half-dozen and half dozen are synonyms defined as:

half-dozen and half dozen: denoting a quantity consisting of six items or units

Other synonyms of half-dozen include 6, six, vi.

half-dozen (adjective)	half dozen (adjective)
denoting a quantity consisting of six items or units	denoting a quantity consisting of six items or units