Dictionary.com
Thesaurus.com

jolly jumper

American  

noun

Nautical.
  1. any light sail set above a skysail; flying kite.


Jolly Jumper British  

noun

  1. a type of fixed sprung baby harness in which an infant may be placed and allowed to bounce up and down for exercise

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of jolly jumper

First recorded in 1880–85