In linguistics, inalienable possession (abbreviated ) is a type of possession in which a noun is obligatorily possessed by its possessor. Nouns or nominal affixes in an inalienable possession relationship cannot exist independently or be "alienated" from their possessor. Inalienable nouns include body parts (such as leg, which is necessarily "someone's leg" even if it is severed from the body), kinship terms (such as mother), and part-whole relations (such as top). Many languages reflect the distinction but vary in how they mark inalienable possession. Cross-linguistically, inalienability correlates with many morphological, syntactic, and semantic properties. In general, the alienable–inalienable distinction is an example of a binary possessive class system in which a language distinguishes two kinds of possession (alienable and inalienable). The alienability distinction is the most common kind of binary possessive class system, but it is not the only one. Some languages have more than two possessive classes. In Papua New Guinea, for example, Anêm has at least 20 classes, and Amele has 32. Statistically, 15–20% of the world's languages have obligatory possession. Comparison to alienable possession With inalienable possession, the two entities have a permanent association in which the possessed has little control over their possessor. For instance, body parts (under normal circumstances) do not change and cannot be removed from their possessor. The following real-world relationships often fall under inalienable possession: Alienable possession, on the other hand, has a less permanent association between the two entities. For instance, most objects may or may not be possessed. When such types of objects are possessed, the possession is alienable. Alienable possession is used generally for tangible items that one might cease to own at some point (such as my money), but inalienable possession generally refers to a perpetual relationship that cannot be readily severed (such as my mother or my arm). The table above outlines some common inalienable relationships, but it is important to note that they are just the most common types of inalienable nouns. Languages with an alienable/inalienable possession distinction differ in which classes fall under each type of possession. However, if a language has such a distinction, kinship roles or body parts (or both) make up some of the entities that are inalienably possessed. Also, languages may make different distinctions within the categories on how many and which entities are treated as inalienable. Moreover, some languages allow the same noun to be either alienable or inalienable. Thus,