N-COUNT
挫折；挫傷；打擊
A knockback is a problem or a rejection which delays your progress or which reverses some of the progress you have made.
例句
The schedule has suffered a knockback...
該計劃遭受了一個打擊。
I must have made more than 100 phone calls and I didn't get a single knockback.
我一定已經(jīng)打過100多個電話了，而且還沒遭到過拒絕。