lily-livered

lily-livered \LIL-ee-LIV-erd\, noun:

Weak or lacking in courage; cowardly; pusillanimous.

But surely, for your own sake, you will not be so lily-livered as to fall into this trap which he has baited for you and let him take the very bread out of your mouth without a struggle.
-- Anthony Trollope, Barchester Towers

He had skin as white as a lily, but he was not lily-livered; he was as strong as a champion at the Shrovetide games.
-- Geoffrey Chaucer and Peter Ackroyd, Canterbury Tales

Lily-livered was first used in English by Shakespeare in Macbeth. The liver was supposedly the seat of passion and was typically dark red or brown. Since a lily is pale and light-colored, a lily-livered person was weak and passionless