1 : to become less strong or intense
The pain/swelling will subside in a couple of hours.
After his anger had subsided, he was able to look at things rationally.
We’ll have to wait until the wind/storm/rain subsides.
2 : to move down to a lower level
The road will remain closed until the water/flood/river subsides.
a place where the ground has subsided [=sunk, settled]