From The Collaborative International Dictionary of English v.0.48 [gcide]:
Dropping \Drop"ping\, n.
1. The action of causing to drop or of letting drop; falling.
[1913 Webster]
2. pl. That which falls in drops; the excrement or dung of
animals; -- often used in the plural.
[1913 Webster]
Dropping bottle, an instrument used to supply small
quantities of a fluid to a test tube or other vessel.
Dropping fire, a continued irregular discharge of firearms.
Dropping tube, a tube for ejecting any liquid in drops.
[1913 Webster]