Rainout, washout, rain delay, and rain stopped play are terms regarding an outdoor event, generally a sporting event, delayed or canceled due to rain, or the threat of rain. It is not to be confused with a type of out in baseball, though a baseball game can be rained out. Delays due to other forms of weather are named "snow delay", "lightning delay", "thunderstorm delay", or "fog delay", while there are many other effects of weather on sport. Also, a night game can be delayed if the floodlight system fails. Often spectators will be issued a ticket for a make up event, known as a "rain check".
Sports typically stopped due to the onset of rain include baseball, golf, tennis, and cricket, where even slightly damp conditions in the latter three sports seriously affect playing quality and the players' safety. In the case of tennis, several venues (such as those of Wimbledon and the Australian Open) have built retractable roofs atop their existing courts and stadiums in the last decade to avert rain delays that could push a tournament further than the final date.
Association football generally plays on through rain, although matches can be if the pitch becomes severely waterlogged or there is lightning in the area, with the latter case being more for the protection of spectators within the metal stands surrounding stadiums. In NCAA play, should lightning be detected by any pitch official, a minimum 30-minute delay and a potential "rainout" can be declared if the lightning continues for a considerable amount of time under the NCAA's all-sports policy regarding lightning.