Based on the Random House Dictionary, © Random House, Inc. 2012.
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| a screen or mat covered with a dark material for shielding a camera lens from excess light or glare. |
| a chattering or flighty, light-headed person. |
pacemaker
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pacemaker pace·mak·er (pās'mā'kər)
n.
A part of the body, such as the specialized mass of cardiac muscle fibers of the sinoatrial node, that sets the pace or rhythm of physiological activity.
Any of several usually miniaturized and surgically implanted electronic devices used to stimulate or regulate contractions of the heart muscle.
A substance whose rate or reaction sets the pace for a series of chain reactions.
The rate-limiting reaction itself.
pace'mak'ing adj. & n.
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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pacemaker  (pās'mā'kər) Pronunciation Key
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Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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pacemaker definition
A group of specialized muscle fibers in the heart that send out impulses to regulate the heartbeat. If the heart's built-in pacemaker does not function properly, an artificial pacemaker may be necessary — a small electrical device that also regulates the heartbeat by sending out impulses. An artificial pacemaker may be placed inside the body surgically or may be worn outside.
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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