pacer

One who paces.

In harness racing, a horse with a gait in which the front and back legs on one side take a step together alternating with the legs on the other side; as opposed to a trotter.

A pacemaker (one who sets the pace in a race).

A timer in an electric toothbrush that indicates how long the user should spend brushing in each part of the mouth.

A mechanical pencil.

A British lightweight railbus diesel multiple unit of class 140, 141, 142, 143 or 144.