From 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]
From WordNet (r) 3.0 (2006) :
lily-livered
adj 1: easily frightened [syn: chicken, chickenhearted,
lily-livered, white-livered, yellow, yellow-
bellied]