I. sim ‧ mer 1 /ˈsɪmə $ -ər/ BrE AmE verb
[ Date: 1600-1700 ; Origin: simper 'to simmer' (15-19 centuries) , perhaps from the sound ]
1 . [intransitive and transitive] to boil gently, or to cook something slowly by boiling it gently:
Bring the soup to the boil and allow it to simmer gently for about half an hour.
2 . [intransitive] if you are simmering with anger, or if anger is simmering in you, you feel very angry but do not show your feelings
simmer with
He was left simmering with rage.
3 . [intransitive] if an argument is simmering, people feel angry with each other but only show it slightly:
The row has been simmering for some time.
Violent revolt was simmering in the country.
simmer down phrasal verb
to become calm again after you have been very angry:
We decided she needed some time to simmer down.
II. simmer 2 BrE AmE noun [singular]
when something is boiling gently:
Bring the vegetables to a simmer.