1. noun
One of a number of terminals or airports which are interchangeable for the purposes of ticketing. <! UA)
2. adjective
a) Differing only by a whole number of complete circles.
When you try to draw two coterminal angles on a circle, you will find that you only get one line.
b) Describing an object in a category, such that there is precisely one morphism that maps that object to every object in the category.
coterminal student
Wikipedia foundation.