adjoin

/ษ™หˆdส’ษ”ษชn/
verb
  1. 1

    To be in contact or connection with.

    โ€œThe living room and dining room adjoin each other.โ€

  2. 2

    To extend an algebraic object (e.g. a field, a ring etc.) by adding to it (an element not belonging to it) and all finite power series of (the element).

Source: https://en.wiktionary.org/wiki/adjoin