verb To cook or undergo heating slowly at or below the boiling point. .mw-parser-output .defdate{font-size:smaller}
The soup simmered on the stove.
verb 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.
verb To be on the point of breaking out into anger; to be agitated.
verb 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.
verb To develop gradually, of an idea or plan.
noun The state or process of simmering.
The kettle was kept on the simmer.
noun Someone who plays a sim (a simulation game), particularly The Sims.
(The addition of quotations indicative of this usage is being sought:)