pro·​trac·​tor | \ prō-ˈtrak-tər How to pronounce protractor (audio) , prə- \

Definition of protractor

1a : one that protracts
b : a muscle that extends a part
2 : an instrument for laying down and measuring angles in drawing and plotting

Examples of protractor in a Sentence

Recent Examples on the Web Inside the fly’s head are protractor and retractor muscles, pulling and pushing at the base of the maxillae. Popular Science, "Evolution made mosquitos into stealthy, sensitive vampires," 20 Oct. 2020 Either get out your high school geometry book to calculate the angles based on the diagonal difference, or use a carpenter’s protractor to measure them. James Dulley, Dallas News, "Do your own finish carpentry to lower costs," 12 Jan. 2020 His physical therapist could only measure his range of motion with a flat protractor, which could lead to serious errors. Courtney Linder, Popular Mechanics, "Using Japanese Paper Art To Heal the Human Body," 16 Oct. 2019 The fixture's arm is clipped to some nearby object to anchor the protractor dial, which must be returned to zero after the initial torque is applied. Popular Mechanics Editors, Popular Mechanics, "How to Use a Torque Wrench to Keep Your Car from Flying Apart," 26 Feb. 2019 There have been sterling silver protractors, and tin cans, and even a greenhouse, as well as bone china to-go coffee cups in Tiffany blue. Reed Krakoff, Town & Country, "Tiffany & Co. Wants to Change the Rules of How to Wear a Diamond," 27 Nov. 2018 Sure, a protractor works, but a sextant does this even better. Rhett Allain, WIRED, "Figure Out Where You Are With Nothing But a Watch and Protractor," 3 May 2018 USA TODAY Sports The compass controversy is over, and the U.S. Golf Association has ruled that Bryson DeChambeau may no longer use his protractor on the course. Kevin Casey, USA TODAY, "USGA rules that Bryson DeChambeau can't use drawing compass on golf course," 6 July 2018 Now hold the protractor upside down and aim the straight part towards the North Star. Rhett Allain, WIRED, "Figure Out Where You Are With Nothing But a Watch and Protractor," 3 May 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'protractor.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of protractor

circa 1611, in the meaning defined at sense 1a

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Time Traveler for protractor

Time Traveler

The first known use of protractor was circa 1611

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Cite this Entry

“Protractor.” Dictionary, Merriam-Webster, Accessed 7 Mar. 2021.

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More Definitions for protractor



English Language Learners Definition of protractor

: a device that has the form of a half circle and that is used for drawing and measuring angles


pro·​trac·​tor | \ prō-ˈtrak-tər How to pronounce protractor (audio) \

Kids Definition of protractor

: an instrument used for drawing and measuring angles


pro·​trac·​tor | \ -tər How to pronounce protractor (audio) \

Medical Definition of protractor

: a muscle that extends a part — compare retractor sense b

More from Merriam-Webster on protractor

Nglish: Translation of protractor for Spanish Speakers Encyclopedia article about protractor

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