The Collaborative International Dictionary of English v.0.48:

Lily-livered \Lil"y-liv`ered\ (l[i^]l"[y^]-l[i^]v`[~e]rd), a.
   White-livered; cowardly.
   [1913 Webster]

WordNet (r) 3.0 (2006):

lily-livered
    adj 1: easily frightened [syn: chicken, chickenhearted,
           lily-livered, white-livered, yellow, yellow-
           bellied]