In linguistics, a possessive affix (from affixum possessivum) is an affix (usually suffix or prefix) attached to a noun to indicate its possessor, much in the manner of possessive adjectives.
Possessive affixes are found in many languages of the world. The World Atlas of Language Structures lists 642 languages with possessive suffixes, possessive prefixes, or both out of a total sample of 902 languages. Possessive suffixes are found in some Austronesian, Uralic, Altaic, Semitic, and Indo-European languages. Complicated systems are found in the Uralic languages; for example, Nenets has 27 (3×3×3) different types of forms distinguish the possessor (first-, second- or third-person), the number of possessors (singular, dual or plural) and the number of objects (singular, dual or plural). That allows Nenets-speakers to express the phrase "we two's many houses" in one word. Mayan languages and Nahuan languages also have possessive prefixes.
Finnish uses possessive suffixes. The number of possessors and their person can be distinguished for the singular and plural except for the third person. However, the construction hides the number of possessed objects when the singular objects are in nominative or genitive case and plural objects in nominative case since käteni may mean either "my hand" (subject or direct object), "of my hand" (genitive) or "my hands" (subject or direct object). For example, the following are the forms of talo (house), declined to show possession:
The grammatical cases are not affected by the possessive suffix except for the accusative case (-n or unmarked), which is left unmarked by anything other than the possessive suffix. The third-person suffix is used only if the possessor is the subject. For example, Mari maalasi talonsa "Mari painted her house", cf. the use of the genitive case in Toni maalasi Marin talon "Toni painted Mari's house". (The -n on the word talon is the accusative case, which is pronounced the same as the genitive case.)
For emphasis or clarification, the possessor can be given outside the word as well, using the genitive case.