[clap.board] n [part trans. of D klaphout stave wood] (ca. 1520) 1 archaic: a size of board for making staves and wainscoting
2: a narrow board usu. thicker at one edge than the other used for siding
3: a pair of hinged boards one of which has a slate with data identifying a piece of film and which are banged together in front of a motion-picture camera at the start of a take to facilitate editing--called also clapper board -- clapboard vt