| a bevel gear that permits rotation of two shafts at different speeds; used on the rear axle of automobiles to allow wheels to rotate at different speeds on curves | the mathematical process of obtaining the derivative of a function |
| a quality that differentiates between similar things | a discrimination between things as different and distinct on the basis of their characteristics or attributes |
| the result of mathematical differentiation; the instantaneous change of one quantity relative to another; df(x)/dx | (biology) the structural adaptation of some body part for a particular function |