Appurtenances are things that belong to and go with something else, the appurtenance being less significant than what it belongs to. The word ultimately derives from Latin appertinere, "to appertain".

In a legal context, an appurtenance could for instance refer to a back-yard that goes with the adjoining house. The idea being expressed is that the back-yard "belongs" to the house, which is the more significant of the two. In 1919, the Supreme Court of Minnesota adopted the following definition of an appurtenance: "That which belongs to something else. Something annexed to another thing more worthy." – Cohen v Whitcomb, (1919 142 Minn 20).