indentation

noun

1.
a concave cut into a surface or edge (as in a coastline)
indenture
2.
the formation of small pits in a surface as a consequence of corrosion
pitting roughness
Derived from:
indent
3.
the space left between the margin and the start of an indented line
indent indention indenture
Derived from:
indent
4.
the act of cutting into an edge with toothlike notches or angular incisions
Derived from:
indent