keep company vs companion

keep company is not a noun while companion is a noun.

Word	Noun	Adjective	Verb	Adverb
keep company	No	No	Yes	No
companion	Yes	No	Yes	No

As verbs, keep company and companion are synonyms defined as:

Other synonyms of keep company include accompany, company.

keep company (noun)	companion (noun)
	a friend who is frequently in the company of another
	one paid to accompany or assist or live with another
	a traveler who accompanies you

keep company (verb)	companion (verb)
be a companion to somebody	be a companion to somebody