[wa.ter.mark] n (1678) 1: a mark indicating the height to which water has risen
2: a marking in paper resulting from differences in thickness usu. produced by pressure of a projecting design in the mold or on a processing roll and visible when the paper is held up to the light; also: the design of or the metal pattern producing the marking
[2]watermark vt (1866) 1: to mark (paper) with a watermark
2: to impress (a given design) as a watermark