Definition of equations:
(n) :
(mathematics) An assertion that two expressions are equal, expressed by writing the two expressions separated by an equal sign; in mathematical problems, equations describe various essential aspects of the problem, each of which contributes to the resolution of the problem in part.
(n) :
The act or process of equating two or more things, or the state of those things being equal (that is, identical).
(n) :
(astronomy) A small correction to observed values to remove the effects of systematic errors in an observation.