indentation

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The act of indenting.
• noun The condition of being indented.
• noun The blank space between a margin and the beginning of an indented line.
• noun A notch or jagged cut in an edge.
• noun A recess, as in a border or coastline.

from The Century Dictionary.

• noun A small hollow or depression; a dent or slight pit, as from a blow or from pressure; an impressed cavity: as, the indentations in a battered shield.
• noun The act of indenting, or the state of being indented; the act of notching, or of cutting into points or inequalities like a row of teeth.
• noun A cut or notch in a margin; a recess or depression.
• noun In printing. See indention.

from the GNU version of the Collaborative International Dictionary of English.

• noun The act of indenting or state of being indented.
• noun A notch or recess, in the margin or border of anything
• noun A recess or sharp depression in any surface.
• noun 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.
• noun The measure of the distance.
• noun indentation of all the lines of a paragraph except the first, which is a full line; also called a hanging indent.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun The act of indenting or state of being indented.
• noun A notch or recess, in the margin or border of anything; as, the indentations of a leaf, of the coast, etc.
• noun A recess or sharp depression in any surface.
• noun 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.
• noun A measure of the distance from the flush line; as, an indentation of one em, or of two ems.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

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