What is the correct form of ‘ours’ with an apostrophe?

Possessive pronouns indicate ownership or possession and do not use apostrophes. Words like 'ours', 'yours', 'his', 'hers', 'its', and 'theirs' inherently show possession without any additional punctuation.

• ours is the correct form. Possessive pronouns like 'ours' already denote possession and therefore do not require an apostrophe. Adding an apostrophe to a possessive pronoun is a common grammatical error.
• our's is incorrect. Apostrophes are used for contractions (e.g., 'it's' for 'it is') or to show possession with nouns (e.g., 'the dog's bone'), but not with possessive pronouns.
• ours' is incorrect. This form is typically used for plural possessive nouns ending in 's', but not for possessive pronouns.
• ours's is incorrect. This is an incorrect and redundant application of the apostrophe.