A jersey is an item of knitted clothing . Its name comes from the island of Jersey , where they were made , traditionally in wool or cotton , with sleeves , worn as a sweater or pullover , as it does not open at the front , unlike a ( cardigan ) ) . A jersey is an item of knitted clothing , traditionally in wool or cotton , with sleeves , worn as a pullover , as it does not open at the front , unlike a cardigan .