back door

noun
  1. 1

    A subsidiary entrance to a building or house at its rear, normally away from the street.

  2. 2

    A means of access, often secret and unprotected, to something.

  3. 3

    A secret means of access to a program or system.

  4. 4

    A rear side door of a car, or at the back of a van.

  5. 5

    The anus, generally used in reference to anal sex.

  6. 6

    The rear side of the hole, furthest from the golfer.

verb
  1. 1

    To attempt to accomplish by indirect means, especially when direct means are proscribed.

  2. 2

    To enter a tube by accelerating from behind; to surf into an already formed hollow wave, in contrast to the normal method of slowing to allow a surfable wave to form.

adjective
  1. 1

    The path of a pitch which starts outside and then slides over the plate.

    โ€œHe has a nasty back door slider.โ€

  2. 2

    Achieved through indirect means.

Source: https://en.wiktionary.org/wiki/back%20door