Phenomenon where two balls, (usually the cue ball and an object ball) have some foreign material (often residual chalk or dirt picked up from unbrushed cloth) between them at the point of contact, resulting in the struck object ball being thrown offline from the expected trajectory, and often also affecting the post-impact path of the cue ball. A typical precaution against cling is to ask for the cue ball and/or object ball to be cleaned by the referee in order to remove chalk that is already on the ball prior to the shot. The table cloth should also be clean. However, no precaution can ward against cling resulting from chalk transferred from the cue tip to the cue ball during a single shot. Coincidental cling can therefore cause unpredictable play and occasionally lead to rudimentary shots being missed at even the highest levels of the game. "Cling" (and derived words like "clung", "clinger", "clinging", etc.) may be used as a mass noun, less commonly as a count noun, as a verb, and rarely as an adjective ("cling is annoying", "two clings in one frame", "they clung", "unintentional clingshot", respectively). Also known as skid, or in the UK, kick (sense 2). See also dead ball, sense 2.