Results
Definition of equation:
 A making equal; equal division; equality; equilibrium.
 A quantity to be applied in computing the mean place or other element of a celestial body; that is, any one of the several quantities to be added to, or taken from, its position as calculated on the hypothesis of a mean uniform motion, in order to find its true position as resulting from its actual and unequal motion.
Synonyms:
equalization, comparison, equating, equality, conic, compare, par, quadratic, equivalency, parity, same, sameness, cubic, mathematical statement, formal statement of equivalence, comparability, equivalence.
Usage examples:

He was too keenly aware of a matter more vital to him than timber or money, a matter in which neither his money nor his timber counted one way or the other, and in which the human equation was everything.
 "The Hidden Places", Bertrand W. Sinclair. 
" In the first place, there is the force represented by f in the equation.
 "Out Like a Light", Gordon Randall Garrett. 
We have probably much evidence, up and down his writings, as to what sort of man the witness was, in what manner he would be likely to see anything and with what personal equation he would relate that which he saw.
 "Edward Caldwell Moore Outline of the History of Christian Thought Since Kant", Edward Moore.