(category theory) A morphism whose codomain is the domain of a parallel pair of morphisms and which forms part of the limit of that parallel pair. Equivalently, a morphism which equalizes a parallel pair of morphisms in a limiting way, which is to say that any other morphism which equalizes that parallel pair factors through this limiting morphism.

“His quick wrister snuck between Crawford's right skate and the post for the equalizer with three minutes left.”

“The way many people here see it, these precautions are the great equalizer when your opponent is a serial killer.”

“Because in this country, in the judicial system, money is a great equalizer.”

equation

The act or process of equating two or more things, or the state of those things being equal (that is, identical).

(mathematics) An assertion that two expressions are equal, expressed by writing the two expressions separated by an equal sign; from which one is to determine a particular quantity.