Weak-kneed

Alternative forms

• weak in the knees

Full definition of weak-kneed

Adjective

1. (figuratively) Lacking will power or strength of character; timid.
• 1903, Jack London, The People of the Abyss, ch. 5:It is incontrovertible that the children grow up into rotten adults, without virility or stamina, a weak-kneed, narrow-chested, listless breed, that crumples up and goes down in the brute struggle for life.
2. (literally)