adjoin (v.) Look up adjoin at Dictionary.com
c.1300, "unite, ally" from Old French ajoin- stem of ajoindre "join together, unite," from Latin adiungere "fasten on, harness, join to," from ad- "to" (see ad-) + iungere "to bind together" (see jugular). Meaning "be contiguous with, be adjacent to" is from late 14c. Related: Adjoined; adjoining.