depth vs deepness

depth and deepness both are nouns.

Word	Noun	Adjective	Verb	Adverb
depth	Yes	No	No	No
deepness	Yes	No	No	No

As nouns, depth and deepness are synonyms defined as:

As nouns, deepness is a hyponym of depth; that is, deepness is a word with a more specific, narrower meaning than depth:

Other hyponyms of depth include profoundness, profundity, draft, draught, penetration, sounding, shallowness.

As nouns, depth and deepness are synonyms defined as:

depth and deepness: the intellectual ability to penetrate deeply into ideas

Other synonyms of depth include astuteness, profoundness, profundity.

depth (noun)	deepness (noun)
the extent downward or backward or inward	the quality of being physically deep
degree of psychological or intellectual profundity	the extent downward or backward or inward
the attribute or quality of being deep, strong, or intense	a low pitch that is loud and voluminous
the intellectual ability to penetrate deeply into ideas	the intellectual ability to penetrate deeply into ideas
(usually plural) a low moral state