Definition of pacemaker
1a
: one that sets the pace for another
b
: one that takes the lead or sets an example
2a
: a group of cells or a body part (such as the sinus node of the heart) that serves to establish and maintain a rhythmic activity
b
: an electrical device for stimulating or steadying the heartbeat or reestablishing the rhythm of an arrested heart
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Merriam-Webster unabridged
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Time Traveler for pacemaker
The first known use of pacemaker was in 1884
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