indentation

nouns

a concave cut into a surface or edge (as in a coastline)
the formation of small pits in a surface as a consequence of corrosion
is derived from
the space left between the margin and the start of an indented line
is derived from
the act of cutting into an edge with toothlike notches or angular incisions
is derived from
is a type of (narrower)
an action that changes the shape of something