Cŭt'-ŏff, n.
n. 1. That which cuts off or shortens, as a nearer passage or road.
Sense 2. (Mach.) A contrivance in the steam-engine for cutting off the passage of steam from the steam-chest to the cylinder, when the piston has moved through part of a stroke, so as to allow the remainder of the stroke to be made by the expansive force of the steam already let in: it economizes fuel and steam.