A possessive or ktetic form (abbreviated poss; from Latin: possessivus; Ancient Greek: κτητικός ktētikós) is a word or grammatical construction used to indicate a relationship of possession in a broad sense. This can include strict ownership, or a number of other types of relation to a greater or lesser degree analogous to it.

Most European languages feature possessive forms associated with personal pronouns, like the English my  , mine  , your , yours  , his  ,hers  and so on. There are two main ways in which these can be used (and a variety of terminologies for each):

, , , , , and so on.

Together with a noun, as in my car, your sisters, his boss. Here the possessive form serves as a possessive determiner. Without an accompanying noun, as in mine is red, I prefer yours, this book is his. A possessive used in this way is called a substantive possessive pronoun, a possessive pronoun or an absolute pronoun. Some languages, including English, also have possessive forms derived from nouns or noun phrases, such as Jane's, cows' and nobody else's. These can be used in the same two ways as the pronoun-derived forms: Jane's office or that one is Jane's.