Merriam-Webster's Collegiate® Dictionary, 11th Edition
JUMPER
I. noun
Date: 1611
a person who jumps,
2. any of various devices operating with a jumping motion, any of several sleds, a connection used to close a break or cut out part of a circuit, any of several jumping animals, jump shot ,
II. noun
Etymology: probably from English dialect jump jumper
Date: 1850
a loose blouse or jacket worn by workmen, a sleeveless one-piece dress worn usually with a blouse, a child's coverall, sweater 2a