\Drop"per\, n. 1. One who, or that which, drops. Specif.: (Fishing) A fly that drops from the leaden above the bob or end fly. 2. A dropping tube. 3. (Mining) A branch vein which drops off from, or leaves, the main lode. 4. (Zo["o]l.) A dog which suddenly drops upon the ground when it sights game, -- formerly a common, and still an occasional, habit of the setter.