heliacal vs sun

heliacal is not a noun while sun is a noun.

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

heliacal (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

heliacal (adjective)	sun (adjective)
pertaining to or near the sun; especially the first rising of a star after and last setting before its invisibility owing to its conjunction with the sun

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