A sweater, jersey, sweater, sweatshirt, jersey or Guernsey is a garment that covers the torso and arms. It is often worn over a shirt, blouse, shirt or top, but can also be used just like a top. Sweaters tend to be, and in earlier times always were, of wool, however, may be cotton, synthetic fibers, or some combination thereof. Sweaters are maintained by washing and the use of a lint roller. The T term has often been confused with the word hood. A sweatshirt has a hood, while a diver is not.

If a sweater has a zipper that goes from the bottom of the top, is usually known as a sweatshirt unless there is a chapel, in which case it is known as a hoodie with zipper [citation needed]. In the U.S., any sweater made of the pile fabric of synthetic fibers like polar fleece, which is called a sweatshirt or do not have a zipper. A hooded sweatshirt that is commonly known as a hoodie. A bridge with an open front with buttons or zipper subject is called a cardigan. A hockey sweater, in the early days of hockey, which is recognized as the people in the 2000s would call a sweater, but has since evolved into a sort of jersey. Therefore, today in North America use the shirt of a hockey player in uniform is traditionally called a sweater, no matter the style.

In British English, a sweater is called a jersey, a jersey or a bridge, the last two terms is the most common name in British English and English in Australia. In South African English, a sweater is always called a jersey. Sleeveless Jerseys are known in American English and English in Australia as vests or jackets. In British English are known as tank tops or slipovers.

A sweater particularly noisy, colorful, decoration and has been known in the United States in the last twenty years as a "Cosby sweater" was named after comedian Bill Cosby's inclination to use them during the run of The Cosby Show.