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antiparallel

[an-tee-par-uh-lel, an-tahy-]
adjective Mathematics, Physics.
  1. (of two vectors) pointing in opposite directions.

Origin of antiparallel

First recorded in 1650–60; anti- + parallel
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
British Dictionary definitions for antiparallel

antiparallel

adjective
  1. physics parallel but pointing in the opposite direction
  2. maths (of vectors) parallel but having opposite directions
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