Phase of vibration Meaning, Definition & Usage

Definitions
  1. any part of the path described by a particle or body in making a complete vibration, in distinction from other parts, as while moving from one extreme to the other, or on one side of the line of rest, in distinction from the opposite. Two particles are said to be in the same phase when they are moving in the same direction and with the same velocity, or in corresponding parts of their paths.

Webster 1913