Solitary confinement is colloquially referred to in American English as "the hotbox", "the hole", "AdSeg" (administrative segregation), the "SHU" (pronounced "shoe"), an acronym for "Special Housing Unit" or "Security Housing Unit"; in Australian English as "the Slot" or "the Pound"; in British English as "the block", "The Segregation Unit", or "the cooler".[1][2] It has also been called prison "'segregation' and 'restrictive housing.'"[3]