pacemaker

n 1: a specialized bit of heart tissue that controls the

heartbeat [syn: {cardiac pacemaker}, {sinoatrial node},

{SA node}]

2: an implanted electronic device that takes over the function

of the natural cardiac pacemaker [syn: {artificial

pacemaker}]

3: a horse used to set the pace in racing [syn: {pacer}, {pacesetter}]