The term 'Crossbar Supporter' refers to a goalpost, which is an upright post used in various sports such as football and rugby. It is typically placed at the end of the playing field and is used to mark the end of the field and to indicate where a goal should be scored. The goalpost is usually composed of two vertical posts connected by a horizontal crossbar. The Crossbar Supporter is the person responsible for ensuring that the goalposts are securely in place and that they remain upright during the game.