When you simmer something on the stove, you heat it gently so it stays just below boiling. The liquid bubbles occasionally, but not as vigorously as a rolling boil. You might simmer a pot of soup for an hour, letting the flavors blend together slowly. Simmering is gentler than boiling: it won't make vegetables fall apart or turn pasta mushy.

The word also describes feelings that stay just below the surface. When anger simmers, it's still there but not exploding outward. You might notice tension simmering between two classmates who aren't speaking to each other, or excitement simmering in your classroom as everyone waits for a field trip announcement.

In cooking, the temperature matters: simmering usually means keeping something around 185-200°F, hot enough to cook slowly but cool enough that only small bubbles occasionally break the surface. Chefs often say “bring to a boil, then reduce to a simmer,” which means turning down the heat after the liquid starts bubbling hard. This technique makes soups richer, sauces thicker, and tough meat more tender.