A French word that literally means “shiver.” Used particularly in reference to poaching.
During poaching, the liquid should be at a very low simmer, at a high just hot enough to make the top of the liquid “shiver”, but not break with bubbles. The French would say that the liquid should “frissonne”; shiver.
This is often the stage, too, at which oil is ready for deep-frying. Use an oil thermometer to be sure.
The French verb to shiver is “frissonner”