Source : Webster's Revised Unabridged Dictionary (1913)

Twang \Twang\, v. i. [imp. & p. p. {Twanged}; p. pr. & vb. n.
   {Twanging}.] [Of imitative origin; cf. {Tang} a sharp sound,
   {Tinkle}.]
   To sound with a quick, harsh noise; to make the sound of a
   tense string pulled and suddenly let go; as, the bowstring
   twanged.