duffer¹ /dufˈər/

1. An unskilful or worthless person (informal)
2. A fogey, a useless old fellow (informal)
3. A counterfeit coin
4. An unproductive mine

• jumping jack
• jumping jacks
• jumping mice
• jumping mouse
• jumping-off place
• jumping-off places
• jumping plant lice
• jumping spider
• jumping spiders
• jump jet
• jump jets
• jump-jockey
• jump-jockeys
• jump leads
• jump off
• jump-off
• jump-offs
• jump on
• jump one's bail
• jump on the bandwagon
• jump out
• jump rope
• jump ropes
• jumps
• jump seat