Meaning of EQUATION in English
( n. )
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.
Webster's Revised Unabridged English Dictionary. Пересмотренный полный словарь английского языка Webster. 2012