monkey jacket

noun3

1. •
   (old-fashioned) A type of close-fitting jacket worn by sailors.

   • We were fain to button up our monkey jackets, and hold to our lips cups of scalding tea with our half frozen fingers. — 1851
2. •
   A semiformal lightweight jacket, usually made of nylon, with striped cuffs and neck, similar to an MA-1 flight jacket.
3. •
   (US, slang) A hospital gown.