Source : Webster's Revised Unabridged Dictionary (1913)

Resonance \Res"o*nance\ (r?z"?-nans), n. [Cf. F. r['e]sonance,
   L. resonantia an echo.]
   1. The act of resounding; the quality or state of being
      resonant.

   2. (Acoustics) A prolongation or increase of any sound,
      either by reflection, as in a cavern or apartment the
      walls of which are not distant enough to return a distinct
      echo, or by the production of vibrations in other bodies,
      as a sounding-board, or the bodies of musical instruments.

   {Pulmonary resonance} (Med.), the sound heard on percussing
      over the lungs.

   {Vocal resonance} (Med.), the sound transmitted to the ear
      when auscultation is made while the patient is speaking.