A sweater, pullover, jumper, jersey or guernsey (clothing) is a relatively heavy garment intended to cover the torso and arms of the human body (though, in some cases, sweaters are made for dogs and occasionally other animals) and usually worn over a shirt, blouse, T-shirt or other top.

Sweaters tend to be, and in earlier times always were, made from wool (typically of sheep, though possibly of alpaca or other type); however, they can be made of cotton, synthetic fibers, or some combination thereof. Sweaters are maintained by washing, and the use of a lint roller.