n The part of a garment that covers the arm. (defdate|from 10th c.)
n A (usually tubular) covering or lining to protect a piece of machinery etc. (defdate|from 19th c.)
n A protectivejacket or case, especially for a record, containing art and information about the contents; also the analogous leaflet found in a packaged CD. (defdate|from 20th c.)