To cook or undergo heating slowly at or below the boiling point.
The soup simmered on the stove.
2
To cause to cook or to cause to undergo heating slowly at or below the boiling point.
Simmer the soup for five minutes, then serve.
3
To be on the point of breaking out into anger; to be agitated.
4
To remain angry with someone or something past the point of exhaustion; to resign oneself to holding a grudge, especially after some failed attempts to resolve a situation.
I tried to get through to him; all that's left for me to do is simmer.