In reference to electrical wiring, a terminal is a passive conductor on an electrical device used to facilitate an electrical connection. It is at this location on a circuit where an electrical connection is either broken or established depending on whether a wire is connected to the terminal properly.
In home wiring applications, the terminal is usually a brass screw. To terminate a wire to the terminal, simply strip the wire and then put a 3/4 loop in the bare copper wire. Next, put the loop around the screw in a clockwise direction and then tighten the screw. You shouldn't have any bare copper wire exposed when you're finish – 1/4 inch at most. The loop in the wire should be orientated in a way that when you tighten the screw, the copper wire tightens around it. Do this by bending the wire in a clockwise direction.
In other wiring applications, the term terminal is used to describe connectors that are attached to the ends of cables.