weak-kneed 
adjective
1Weak and shaky as a result of fear or excitement: she still felt weak-kneed whenever he came towards her...
- His eyes met mine and I felt curiously light-headed and weak-kneed. I tore my eyes away with an effort, trying not to think about him.
- It wasn't exertion that left him weak-kneed and trembling, but rather the gut-wrenching horror of Joe's scream and his pleas for mercy.
- Exercise seemed to help the nausea, although I was weak-kneed with hunger, cold, and probably fear.
1.1Lacking in resolve or courage; cowardly: no one could say that our news programmes have been weak-kneed in their coverage the other two, a couple of weak-kneed cowards, had run off...
- Despite past criticism for being weak-kneed and soft on dictators, the ex-President has advocated persevering in negotiations even with those nations Washington views as hostile.
- To put this another way, the instinctive worry about such things as patenting the gene pool or privatizing the air does not come solely from nostalgia or a weak-kneed fear of change.
- Cardiff's weak-kneed Liberals are trembling in case anyone finds out.
