1. A flat key or strip that its into a groove or slot between two parts. Alternately, the groove or slot into which it fits.
2. A long, flat, pliable strip of wood, used to strength two pieces of wood by joining. The strip (spline) fits into a groove cut into the two joined pieces.
3. The raised ridges evenly spaced around the circumference of a drive shaft or axle.
Electrical connector consisting of a threaded bolt with a slot through the threaded part, with wires placed in the slot and a nut, which has an attached solid piece of metal that fits into the slot, threaded into the bolt. Split-bolt connectors are used when the joining wires are too large to be connected by wire nuts.
Double electrical receptacle which has one half wired to one circuit with the other half wired to a different circuit. This allows for greater flexibility in use of high current drawing appliances, since they will not overpower one circuit and also protects against total loss of electricity if one circuit blows out.
Clamp which is used to repair a pipe lead at a gasket in a bell and spigot joint by having one ring fit the bell side and the other the spigot side of the joint, with both being held together by interconnecting bolts, spanning the joint. A gasket is attached around the spigot end. When the bolts are tightened, the rings are drawn together, forcing the gasket into the bell to seal the leak.