A motion is said to be oscillatory if it is repetitive in which an object repeats the same movement over and over.
The body oscillates from its mean position. The maximum distance it covers is called the amplitude of oscillation and how many oscillations it performs in 1 second is called the frequency of oscillation. The time it took for one oscillation is called the time period of oscillation.
If there is no frictional force, the oscillatory motion is forever.
The motion of a swinging mass attached to a spring is an example of oscillatory motion.
The motion of a swinging pendulum is an example of oscillatory Motion.
Alternating current is an electrical example of oscillatory motion