The Collaborative International Dictionary of English v.0.48:

Eyewash \Eye"wash\, n.
   See Eyewater.
   [1913 Webster]

WordNet (r) 3.0 (2006):

eyewash
    n 1: lotion consisting of a solution used as a cleanser for the
         eyes [syn: eye-lotion, eyewash, collyrium]