A cork or float on a fishing line used to keep bait at a desired depth and indicate when a fish bites; someone or something that bobs.
From bob + -er (agent suffix). The fishing equipment sense developed in the 19th century as fishing became increasingly recreational. The -er suffix creates a noun meaning 'one who bobs' or 'a thing that bobs,' following standard English word-formation patterns.
Fishing bobbers are brilliant examples of simple technology solving a problem—they let you see exactly when something underwater is interested in your bait, which is why kids still love watching them today!
Complete word intelligence in one call. Free tier — 50 lookups/day.