A gadget is something simple you can put together to help make things easier for you in the outdoors, at home, or wherever you are. There are hundreds of outdoor gadgets you can make if you want to. Another Scouting member, one of your leaders, or your parents can probably suggest a few that might be fun to try. 
Gadgets in Scouts Canada Wiki
- Wording from Page 114 of The Cub Book.