ultraviolet vs sun-ray

ultraviolet and sun-ray both are nouns.

Word	Noun	Adjective	Verb	Adverb
ultraviolet	Yes	Yes	No	No
sun-ray	Yes	No	No	No

As nouns, sun-ray is a hyponym of ultraviolet; that is, sun-ray is a word with a more specific, narrower meaning than ultraviolet:

ultraviolet: radiation lying in the ultraviolet range; wave lengths shorter than light but longer than X rays
sun-ray: a ray of artificial ultraviolet light from a sunray lamp

Other hyponyms of ultraviolet include sunray.

ultraviolet (noun)	sun-ray (noun)
radiation lying in the ultraviolet range; wave lengths shorter than light but longer than X rays	a ray of artificial ultraviolet light from a sunray lamp

ultraviolet (adjective)	sun-ray (adjective)
having or employing wavelengths shorter than light but longer than X-rays; lying outside the visible spectrum at its violet end