indentation vs concave shape

indentation and concave shape both are nouns.

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

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

Other hypernyms of indentation include concavity, incurvation, incurvature.

indentation (noun)	concave shape (noun)
the act of cutting into an edge with toothlike notches or angular incisions	a shape that curves or bends inward
the space left between the margin and the start of an indented line
the formation of small pits in a surface as a consequence of corrosion
a concave cut into a surface or edge (as in a coastline)