The geometric equivalent of inserting a missing square piece to complete a three-piece square puzzle.
It's a pity that most math teachers and textbooks fail to point out to students some creative uses of the completing the square, other than using it as a key step to derive the quadratic formula.
by MathPlus August 25, 2016
(v.) The act of hooking up with your ex's current partner's ex after discovering that your ex is hooking up with the target's ex.
Ex: Jenny and Alan used to date. Chrissy and Dave are dating, but Chrissy leaves Dave for Alan. When Dave and Jenny hook up, they are "completing the square".
by thedl February 28, 2008