half-hour vs hour

half-hour and hour both are nouns.

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

half-hour (noun)	hour (noun)
a half of an hour	distance measured by the time taken to cover it
	a period of time equal to 1/24th of a day
	clock time
	a special and memorable period