Jumper/ˈdʒʌmpər/ Definition 1 of 6Pro Tip 1/3British vs American Remember 'jumper' means 'sweater' in the UK, while Americans may think of a dress. I'm packing jumpers for my trip to London this December. Pro Tip 2/3Casual Wear 'Jumper' usually refers to casual, cozy clothing instead of formal wear. She wore her favourite jumper to the coffee shop. Pro Tip 3/3Seasonal Clothing Jumpers are associated with cooler weather, like autumn and winter. Every winter, he pulls out his collection of woolly jumpers.