A critter is an informal, friendly word for a creature or animal, especially a small one. When you spot a critter scurrying across your backyard, it might be a squirrel, a chipmunk, or even a field mouse. Farmers talk about critters in the barn, meaning the various animals living there, from chickens to barn cats to the occasional raccoon.

The word has a warm, down-to-earth feeling to it. People usually don't call lions or elephants critters; they use it for smaller, everyday animals you might encounter in ordinary life. A science teacher examining pond water might peer through a microscope and say, “Look at all these tiny critters swimming around!” when showing students the microscopic organisms living in a single drop.

Sometimes people use critter playfully for any living thing, even insects or pets. You might hear someone say, “What kind of critter is that?” when they spot an unfamiliar bug, or affectionately call the family dog “a funny little critter.” The word suggests a casual, accepting attitude toward the animal world around us.