adjective Mathematics, Physics.
(of two vectors) pointing in opposite directions.
Origin of antiparallel
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
physics parallel but pointing in the opposite direction
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