Traditionally, a jersey is an item of knitted clothing, generally made of wool or cotton, with sleeves, worn as a pullover, as it does not open at the front, unlike a cardigan.
It is usually close-fitting and machine knitted in contrast to a guernsey that is more often hand knit with a thicker yarn.
[1] The garment's name originates from the British Crown Dependency of Jersey in the English Channel.
The island became a large exporter of knitted goods in the Elizabethan era.
[2] The name is also used more generally to refer to the knit fabric particular to the sweater.