The Collaborative International Dictionary
hanging indent
Indentation \In`den*ta"tion\, n.
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.
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(Print.)
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.
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The measure of the distance; as, an indentation of one em, or of two ems.
Hanging indentation, or Reverse indentation, indentation of all the lines of a paragraph except the first, which is a full line; also called a hanging indent.
Wikipedia
Hanging Indent