[proh-trak-ter, pruh-]


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

From Medieval Latin, dating back to 1605–15; see origin at protract, -tor Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for protractor

Historical Examples of protractor

  • The protractor has a graduated disk, and is adjustable so it can be disposed at any angle.

  • He was using a protractor, which was divided into Galactic degrees.

    The Players

    Everett B. Cole

  • Protractor: that which extends or lengthens out: applied to muscles.

  • We'll start with the one with the coconut ice and the protractor, please.

    The Judge

    Rebecca West

  • At that point find, by means of a protractor, the angle a projection of the chord makes with the face of the beam.

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

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

protractor in Medicine




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.