The apostrophe ( ’ or ' ) is a  punctuation mark, and sometimes a diacritic mark, in languages written in the Latin alphabet. In English, it has two main functions: it marks omissions; and it assists in marking the possessives of all nouns and many pronouns. (In strictly limited cases, it is sometimes also allowed to assist in marking plurals, but most authorities are now against such usage; see below.) According to the OED, the word comes ultimately from Greek ἡ ἀπόστροφος [προσῳδία] (, the [accent of] "turning away", or elision), through Latin and French.