horse around vs fool

horse around is not a noun while fool is a noun.

Word	Noun	Adjective	Verb	Adverb
horse around	No	No	Yes	No
fool	Yes	No	Yes	No

As verbs, horse around and fool are synonyms defined as:

Other synonyms of horse around include arse around, fool around.

horse around (noun)	fool (noun)
	a person who lacks good judgment
	a person who is gullible and easy to take advantage of
	a professional clown employed to entertain a king or nobleman in the Middle Ages

horse around (verb)	fool (verb)
indulge in horseplay	indulge in horseplay
	fool or hoax
	spend frivolously and unwisely
	make a fool or dupe of