comet vs nucleus

comet and nucleus both are nouns.

Word	Noun	Adjective	Verb	Adverb
comet	Yes	No	No	No
nucleus	Yes	No	No	No

comet (noun)	nucleus (noun)
(astronomy) a relatively small extraterrestrial body consisting of a frozen mass that travels around the sun in a highly elliptical orbit	a part of the cell containing DNA and RNA and responsible for growth and reproduction
	any histologically identifiable mass of neural cell bodies in the brain or spinal cord
	the central structure of the lens that is surrounded by the cortex
	a small group of indispensable persons or things
	the positively charged dense center of an atom
	(astronomy) the center of the head of a comet; consists of small solid particles of ice and frozen gas that vaporizes on approaching the sun to form the coma and tail