differential

Etymology

Morphologically different + -ial.

adj

1. Of or pertaining to a difference.
   differential characteristics
   [Caspar Schetz, Baron of Grobbendonck] was regularly in the pay of Sir Thomas Gresham, to whom he produced differential favours, and by whose government he was rewarded by gold chains and presents of hard cash, bestowed as secretly as the equivalent was conveyed adroitly. 1856, John Lothrop Motley, The Rise of the Dutch Republic: A History, volume 1
2. Dependent on, or making a difference; distinctive.
3. Having differences in speed or direction of motion.
4. (mathematics) Of or pertaining to differentiation or the differential calculus.

noun

1. The differential gear in an automobile, etc.
2. A qualitative or quantitative difference between similar or comparable things.
3. (mathematics) An infinitesimal change in a variable, or the result of differentiation.
4. One of two coils of conducting wire so related to one another or to a magnet or armature common to both, that one coil produces polar action contrary to that of the other.
5. A form of conductor used for dividing and distributing the current to a series of electric lamps so as to maintain equal action in all.