adj. or adv. (of rotation, an angle, etc.) in the same direction as that conventionally taken by the hands of a clock. If a horizontal line segment has its left-hand end, A, fixed, its right-hand end, B, moves clockwise when it moves downwards as shown below.By convention, for the purpose of measuring angles, fixing points by polar coordinates, etc., this is taken to be the negative direction. Compare anticlockwise.