Longman Dictionary of Contemporary English - equation

~ n 1 a statement in mathematics, showing that two quantities are equal  (In the equation 2x + 1 = 7, what is x?) 2 enter into the equation/be part of the equation to be a fact that affects a particular problem, situation, idea etc  (We hadn't realized that cost would enter into the equation at all.) 3 the act of equating two things