Frock has been used since Middle Englishas the name for an article of clothing for men and women (see also clothing terminology). History of the frock Originally, a frock was a loose, long garment with wide, full sleeves, such as the habit of a monk or priest, commonly belted. (This is the origin of the modern term defrock or unfrock, meaning "to eject from the priesthood"). The term has been continually applied to various types of clothing, generally denoting a loosely fitted garment: From th… (More on Frock)