Bob meaning : A bobbing motion; a quick up and down movement. A curtsy. A bobber (buoyant fishing device). Any of various hesperiid butterflies. To move gently and vertically, in either a single motion or repeatedly up and down, at or near the surface of a body of water, or similar medium. To move (something) as though it were bobbing in water. To curtsy. To strike with a quick, light blow; to tap.