[sim.mer] vb sim.mered ; sim.mer.ing [alter. of E dial. simper, fr. ME simperen, of imit. origin] vi (1653) 1: to stew gently below or just at the boiling point
2. a: to be in a state of incipient development: ferment "ideas ~ing in the back of my mind" b: to be in inward turmoil: seethe ~ vt: to cook slowly in a liquid just below the boiling point
[2]simmer n (1809): the state of simmering