sunbathe vs sun

sunbathe is not a noun while sun is a noun.

Word	Noun	Adjective	Verb	Adverb
sunbathe	No	No	Yes	No
sun	Yes	No	Yes	No

As verbs, sunbathe and sun are synonyms defined as:

sunbathe (noun)	sun (noun)
	any star around which a planetary system revolves
	the star that is the source of light and heat for the planets in the solar system
	a person considered as a source of warmth or energy or glory etc
	the rays of the sun

sunbathe (verb)	sun (verb)
expose one's body to the sun	expose one's body to the sun
	expose to the rays of the sun or affect by exposure to the sun