1. One who, or that which, drops. Specif., a fly that drops from the leaden above the bob or end fly.
2. A dropping tube.
3. (Science: chemical) a branch vein which drops off from, or leaves, the main lode.
4. (Science: zoology) a dog which suddenly drops upon the ground when it sights game, formerly a common, and still an occasional, habit of the setter.