A buoyant device (frequently made of cork) attached to a line so as to suspend the end of the line with the hook (and bait or lure) above the bottom.(noun)
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Use "bobber" in a sentence
"BOBBER RIG When you're fishing near a prominent obstruction, around the mouth of atributary, or over weeds, using a bobber is a good approach (you want it as small as possible to minimize the resistance when a pike takes the bait and runs)."
"While a beer can bobber doesn't really do anything for me, I was highly impressed by the shear number of brew brands offered in bobber form."
"While fishing along side a creek or pond, I may think how different a dragonfly appears and watch it fly to the next area of concern, while my bobber is submerging and dropping like the NYSE."