let up phrasal verb ( see also ↑ let )
1 . to become less severe or harmful:
The wind had dropped and the rain gradually let up.
2 . to be less severe, unkind, or violent towards someone:
Even when the crowd had scattered, the police didn’t let up.
3 . to stop working as hard as you were:
You’re doing really well, but you can’t afford to let up now.