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[proh-trak-ter, pruh-] /proʊˈtræk tər, prə-/
a person or thing that protracts.
(in surveying, mathematics, etc.) an instrument having a graduated arc for plotting or measuring angles.
Anatomy. a muscle that causes a part to protrude.
Origin of protractor
1605-15; < Medieval Latin; see protract, -tor Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for protractor
  • The protractor muscles of their beaks allow them to pry and to probe better than other birds.
  • He hates that people know he's good at math and carries around a protractor.
  • Glue the protractor to a piece of cardboard as shown in the illustration.
  • The first part is a hands-on activity using string, chalk, and protractor.
  • The angular position on the protractor indicated by the pointer was recorded.
  • The horizontal accelerometer is a protractor with a suspended weight.
  • They estimate the correct position, then measure their guess with a protractor to see how close they were.
  • Plotting instruments and the circular protractor were used to draw their maps.
British Dictionary definitions for protractor


an instrument for measuring or drawing angles on paper, usually a flat semicircular transparent plastic sheet graduated in degrees
a person or thing that protracts
a surgical instrument for removing a bullet from the body
(anatomy) a former term for extensor
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for protractor

1610s, "one who lengthens (an action)," from Medieval Latin protractor, agent noun from Latin protrahere "to draw forward" (see protraction); sense of "instrument for drawing angles" first recorded 1650s.

Online Etymology Dictionary, © 2010 Douglas Harper
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protractor in Medicine

protractor pro·trac·tor (prō-trāk'tər, prə-)
A muscle that extends a limb or other part.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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