Ordinary differential equation

differential equation containing one or more functions of one independent variable and its derivatives
The trajectory of a projectile launched from a cannon follows a curve determined by an ordinary differential equation that is derived from Newton's second law.

An ordinary differential equation (often shortened to ODE) is a differential equation which contains one free variable, and its derivatives. Ordinary differential equations are used for many scientific models and predictions. The term ordinary is used to differentiate them from partial differential equations, which contain more than one free variable, and their derivatives.