'clapperboard' definitions:

Definition of 'clapperboard'

From: WordNet
noun
Photographic equipment used to synchronize sound and motion picture; boards held in front of a movie camera are banged together

Definition of 'clapperboard'

From: GCIDE
  • clapperboard \clap"per*board`\ (kl[a^]p"p[~e]r*b[=o]rd`), n. a device which synchronizes sound and picture while making a motion picture, consisting of boards held in front of a movie camera, which are are banged together. [WordNet 1.5]