Source : Webster's Revised Unabridged Dictionary (1913)

Dingdong theory \Ding"dong` the"o*ry\ (Philol.)
   The theory which maintains that the primitive elements of
   language are reflex expressions induced by sensory
   impressions; that is, as stated by Max M["u]ller, the
   creative faculty gave to each general conception as it
   thrilled for the first time through the brain a phonetic
   expression; -- jocosely so called from the analogy of the
   sound of a bell induced by the stroke of the clapper.