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bisector

American  
[bahy-sek-ter, bahy-sek-] / baɪˈsɛk tər, ˈbaɪ sɛk- /

noun

Geometry.
  1. a line or plane that bisects an angle or line segment.


bisector British  
/ baɪˈsɛktə /

noun

  1. a straight line or plane that bisects an angle

  2. a line or plane that bisects another line

"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

Etymology

Origin of bisector

First recorded in 1860–65; bisect + -or 2