Question

What is vibration?...​

Answer 1

Answer:

Vibration is defined¹ as The oscillating, reciprocating, or other periodic motion of a rigid or elastic body or medium forced from a position or state of equilibrium. Measurement devices are available that can measure the displacement, velocity or acceleration of this periodic motion.

Answer 2

Answer:

"Vibrations are mechanical oscillations. They can be described by frequency, amplitude, phase and shape. ... Vibrations can naturally emerge in systems that allow transfer between different types of energy, e.g., between potential and kinetic energy (pendulum) or between elastic and kinetic energy (spring-mass oscillator)."