Sleeper

Sleeper, a term used with many technical applications for a piece of timber, metal, &c., used as a support; in carpentry it is such a piece of timber laid on low cross walls as a plate to receive ground joists; in shipbuilding, a strengthening timber for the bows and stern frame; the most frequent use of the term is for a timber or steel support on which the chairs are fixed for carrying the rails on a railway; in America these are called ties " (see Railways). The common explanation of the origin of the word is to connect it with " sleep," the timbers supposed to be lying at rest. The real source of the word is the Norwegian sleep, a piece of timber used for dragging things over, a roller, especially used of timbers laid in a row in making a road. This word Skeat (Etymol. Dict., 1898) connects with " slab," a flat piece of stone or wood. The French term dormant is used in carpentry, but as part of the frame of a window or door.