Definition of: possessive

(pə·zes′iv) adjective
1. Pertaining to or expressive of possession.
2. Gram. Designating a case of the noun or pronoun that denotes possession, origin, or the like. In English, this is formed in nouns by adding 's to the singular and to irregular plurals: John's book; men's souls; the boss's office; and a simple apostrophe to the regular plural and sometimes to singulars and proper names ending in a sibilant: boys' shoes; Dickens' (or Dickens's) writings; James' (or James's) brother. See also –'s¹. Pronouns in the possessive case have special forms, as my, mine, his, her, hers, its, our, ours, your, yours, their, theirs, whose. By some grammarians possessive nouns and pronouns are called possessive adjectives.
—noun Gram.
1. The possessive case.
2. A possessive form or construction.
—double possessive A redundant possessive. Example: a book of Mike's.