Weak and cowardly

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
"cowardly," 1605, in "Macbeth;" from lily (in its color sense of "pale, bloodless") + liver (n.1), which was a supposed seat of love and passion. A healthy liver is typically dark reddish-brown.

Longman Dictionary of Contemporary English Word definitions in Longman Dictionary of Contemporary English
adjective EXAMPLES FROM CORPUS ▪ Because no one hearing his name thinks this Government is run by a bunch of lily-livered limousine-liberals. ▪ Not a city for the lily-livered or faint-hearted. ▪ The Government are still lily-livered in that respect.

WordNet Word definitions in WordNet
adj. easily frightened [syn: chicken , chickenhearted , white-livered , yellow , yellow-bellied ]

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Lily-livered \Lil"y-liv`ered\ (l[i^]l"[y^]-l[i^]v`[~e]rd), a. White-livered; cowardly.

Wiktionary Word definitions in Wiktionary
a. (context idiomatic English) coward, lacking bravery.