1. (

• pacesetter ,
• pacemaker

) a leading instance in its field; "the new policy will be a pacesetter in community relations" ;

2. (

• pacemaker ,
• cardiac_pacemaker ,
• sinoatrial_node ,
• SA_node

) a specialized bit of heart tissue that controls the heartbeat ;

3. (

• pacemaker ,
• artificial_pacemaker

) an implanted electronic device that takes over the function of the natural cardiac pacemaker ;

4. (

• pacer ,
• pacemaker ,
• pacesetter

) a horse used to set the pace in racing ;