Theinstantaneousmagnitudeofanoscillatingquantitysuchassoundpressure.Thepeakamplitudeisthemaximumvalue.Inavibratingobject,amplitudeismeasuredandexpressedinthreeways:Displacement,VelocityandAcceleration.Amplitudeisalsothey-axisofthevibrationtimewaveformandspectrum;ithelpsdefinetheseverityofthevibration