Oscillation is the repetitive movement of something between two different extreme points about a central axis. The classic example is an energy wave such as a sound wave or a light wave. The wave oscillates between two opposite amplitudes about a central null line. The distance between two of these peaks of the same amplitude is called a wavelength. Oscillation also occurs on the macroscale as well. A pendulum and a weight attached to a spring are examples of oscillating motion. Not all examples of oscillation are from the physical sciences. Economic cycles and social science cycles can also be an example of oscillating behaviour.
Oscillation: Any quantity or body is in a state of oscillation when its value or motion is continually changing so that it passes through maximum and minimum values or positions. (Simon Fraser University)