Source : Webster's Revised Unabridged Dictionary (1913)

Dingdong \Ding"dong`\, n. [See {Ding}.]
   1. The sound of, or as of, repeated strokes on a metallic
      body, as a bell; a repeated and monotonous sound.

   2. (Horol.) An attachment to a clock by which the quarter
      hours are struck upon bells of different tones.

Source : WordNet®

dingdong
     adv : heartily or earnestly; "They fell to work dingdong"
     v : go `ding dong', like a bell [syn: {ding}, {dong}]