Wordnet 3.0
ADJECTIVE (1)
1. 
 of an achromatic color of any lightness intermediate between the extremes of white and black; 
- Example: "the little grey cells"- Example: "gray flannel suit"- Example: "a man with greyish hair"[syn: grey, gray, greyish, grayish]
The Collaborative International Dictionary of English v.0.48:
greyish \grey"ish\ adj.
   somewhat gray.
   Syn: grayish.
        [WordNet 1.5]
WordNet (r) 3.0 (2006):
greyish
    adj 1: of an achromatic color of any lightness intermediate
           between the extremes of white and black; "the little grey
           cells"; "gray flannel suit"; "a man with greyish hair"
           [syn: grey, gray, greyish, grayish]