In typical English usage, a back door is the door around the back of a building. Thus, "employees must enter the store via the back door." Several concepts are named after it:

• In computing, a backdoor is a hidden method for bypassing normal authentication systems.
• To backdoor is to do something, such as getting a job, through having some unfair advantage. For example, "I backdoored my admission to Yale. I bribed the admissions officer." See also guanxi.
• Back Door were a British jazz trio, drums sax and bass guitar, who played in the bar of the highest pub on the Yorkshire moors during the late 1970s. They made two albums, Back Door and 8th Street Nites. Their use of the bass guitar was ahead of its time.