Noun

1. A semiformal lightweight jacket, usually made of nylon, with striped cuffs and neck, similar to an MA-1 flight jacket.
2. A type of close-fit jacket worn by sailors
   • 1820, Francis Forbes, "The Banks of Newfoundland":

     You bully boys of Liverpool, I'll have you to beware,

     When you sail on them packet ships, no dungaree jumpers wear;

     But have a big monkey jacket all ready to your hand,

     For there blows some cold nor'westers on the Banks of Newfoundland.