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circular measure

noun
  1. a measurement system for circles: 1 circle = 360 degrees (4 quadrants); 1 quadrant = 90 degrees; 1 degree = 60 minutes; 1 minute = 60 seconds.

Origin of circular measure

First recorded in 1870–75
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
British Dictionary definitions for circular measure

circular measure

noun
  1. the measurement of an angle in radians
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