subside

to sink down or become less active

Roots

sed / sit: sit, settle, or be seated
sub-: under, below, or after

Other words with the sed / sit root

dissident: open disagreement from the group
sit: to rest in a seated position
supersede: to replace or take the place of

Subside keeps the sitting-down image: pressure, water, pain, or noise settles lower.

The panic subsided once the instructions became clear.

Sub- gives under or lower; sed / sit gives sitting or settling. When water, fear, noise, swelling, or anger subsides, it settles down instead of pressing upward.