Indentation

The act of indenting or state of being indented.

A notch or recess, in the margin or border of anything; as, the indentations of a leaf, of the coast, etc.

A recess or sharp depression in any surface.

The act of beginning a line or series of lines at a little distance within the flush line of the column or page, as in the common way of beginning the first line of a paragraph.

The measure of the distance; as, an indentation of one em, or of two ems.

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