impression vs concave shape

impression and concave shape both are nouns.

Word	Noun	Adjective	Verb	Adverb
impression	Yes	No	No	No
concave shape	Yes	No	No	No

As nouns, concave shape is a hypernym of impression; that is, concave shape is a word with a broader meaning than impression:

Other hypernyms of impression include concavity, incurvation, incurvature.

impression (noun)	concave shape (noun)
an impressionistic portrayal of a person	a shape that curves or bends inward
the act of pressing one thing on or into the surface of another
(dentistry) an imprint of the teeth and gums in wax or plaster
an outward appearance
a vague idea in which some confidence is placed
a clear and telling mental image
a symbol that is the result of printing or engraving
all the copies of a work printed at one time
a concavity in a surface produced by pressing