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