The Collaborative International Dictionary of English v.0.48:
eyeliner \eye"lin`er\ ([imac]"l[imac]`n[~e]r), n. a cosmetic powder of a dark tint, applied to the eyelid close to the base of the eyelashes to accentuate the eyes. Compare eye shadow. [PJC]WordNet (r) 3.0 (2006):
eyeliner n 1: makeup applied to emphasize the shape of the eyes