A Dropper

1. A utensil for dispensing a single drop of liquid at a time.
2. One who drops something, especially one who drops a specific item to cause mischief.
3. (computing) A software component designed to install malware on a target system.
4. (fishing) A fly that drops from the leaden above the bob or end fly.
5. (mining) A branch vein which drops off from, or leaves, the main lode.
6. A dog which suddenly drops upon the ground when it sights game.
7. (slang) A person who uses fraudulent cheques.