What is the meaning of Pacemaker?

A set of nerves which stimulate the heart to beat.

A medical implement that is used to stimulate a heart to beat by simulating the action of the natural pacemaker.

One who sets the pace in a race, to guide the others.

pacemaker (device)

pacemaker

pacemaker

a pacemaker, one who sets the pace

a pacemaker, an implant that stimulates the heart to beat

Source: wiktionary.org