What is a word that includes both parallel and antiparallel ?
This bothers me all the time when I do my math or physics homework.
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It seems that direction would be a good hypernym. Parallel is a way of describing a direction or orientation of an object:
Parallel 1. a : extending in the same direction, everywhere equidistant, and not meeting
Antiparallel is similar
Antiparallel: parallel but oppositely directed or oriented
The word you need is collinear. Collinear vectors could have same or opposite directions. https://math.tutorvista.com/calculus/collinear-vectors.html