Adjoin/əˈdʒɔɪn/ Definition 1 of 2Pro Tip 1/3Physical Proximity Used to express direct physical contact or closeness between buildings, objects, or areas. The hotel adjoins the beach, offering stunning sea views. Pro Tip 2/3Shared Borders Indicates that two areas or surfaces share a common border or edge. Their backyards adjoin, so they built a gate between them. Pro Tip 3/3No Gap Emphasizes the absence of space or a gap between adjoining things. The rows of houses adjoin closely, forming a continuous street facade.