• noun a movable structure with a large flat surface, typically made of slatted wood but occasionally of other materials (such as canvas), which is placed just outside the boundary directly behind either of the wickets in order to assist the batsman by enhancing the visibility of the bowled ball. Sightscreens are traditionally white, but black sightscreens are used in day-night games played with white balls. Some modern sightscreens have surfaces that can be changed between overs, showing advertisements when the bowler is operating from the other end.