"to make a cut," 1540s, from French inciser (15c.), from Old French enciser "cut, cut out, slice" (12c.), from Latin incisus, past participle of incidere "to cut into, cut open, engrave," from in- "into, in, on, upon" (from PIE root *en "in") + -cidere, combining form of caedere "to cut" (from PIE root *kae-id- "to strike"). In geology, of rivers, from 1893. Related: Incised; incising.