gravity vs sombreness

gravity and sombreness both are nouns.

Word	Noun	Adjective	Verb	Adverb
gravity	Yes	No	No	No
sombreness	Yes	No	No	No

As nouns, gravity and sombreness are synonyms defined as:

Other synonyms of gravity include graveness, soberness, sobriety, somberness.

gravity (noun)	sombreness (noun)
a manner that is serious and solemn	a manner that is serious and solemn
a solemn and dignified feeling	a feeling of melancholy apprehension
(physics) the force of attraction between all masses in the universe; especially the attraction of the earth's mass for bodies near its surface	a state of partial or total darkness