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1. A leading instance in its field
   "the new policy will be a pacemaker in community relations";
   - pacesetter
    
2. A specialized bit of heart tissue that controls the heartbeat
   - cardiac pacemaker, sinoatrial node, SA node
    
3. An implanted electronic device that takes over the function of the natural cardiac pacemaker
   - artificial pacemaker
    
4. A horse used to set the pace in racing
   - pacer, pacesetter

Derived forms: pacemakers

Type of: bangtail [US, informal], cardiac muscle, electronic device, example, exemplar, good example, heart muscle, model, neddy [Austral, informal], pony [informal], race horse, racehorse

Encyclopedia: Pacemaker