noun /ˈdʒʌmpə(r)/ /ˈdʒʌmpər/
a collarless sleeveless dress, typically worn over a blouse.

a piece of clothing for the upper part of the body, made of wool or cotton, with long sleeves (= arms) and no buttons

a sweater.

a woolly jumper

The jumper comes in assorted colours.

My new jumper got mangled in the washing machine.

a person or animal that jumps.

He's a good jumper.