indent (v.2) Look up indent at Dictionary.com
"to dent or press in," c. 1400, from in (adv.) + dent (v.). Etymologically distinct from indent (v.1) but felt as the same.
indent (n.) Look up indent at Dictionary.com
"cut or notch in a margin," 1590s, from indent (v.1). A supposed earlier noun sense of "a written agreement" (late 15c.) is described in Middle English Dictionary as "scribal abbrev. of endenture."
indent (v.1) Look up indent at Dictionary.com
early 15c., indenten, endenten "to make notches; to give (something) a toothed or jagged appearance," also "to make a legal indenture, make a written formal agreement or contract," from Old French endenter "to notch or dent, give a serrated edge to" (12c.) and directly from Medieval Latin indentare "to furnish with teeth," from in- "into, in, on, upon" (from PIE root *en "in") + verb from Latin dens (genitive dentis) "tooth" (from PIE root *dent- "tooth").
An indented document was usually, if not always, written in two or more identical versions. Orig. these were written on a single sheet of parchment and then cut apart along a zigzag, or 'indented' line. Each party to the agreement retained one copy, which he could readily authenticate by matching its serrate edge with that of another copy. [Middle English Dictionary]
The printing sense "insert white space to force text inward" is first attested 1670s. Related: Indented (late 14c.); indenting.