mid 16th century (denoting the omission of one or more letters): via late Latin, from Greek apostrophos 'accent of elision', from apostrephein 'turn away', from apo 'from' + strephein 'to turn'
Many people are uncertain when to use an apostrophe, and this confusion is probably increased by the fact that it is often omitted in company names (e.g. Barclays Bank). The apostrophe should be used when indicating possession (Sue’s cat) or the omission of letters or numbers (he’s gone, 1 Jan. ’09). It should not be used in forming the plural of ordinary words, as in apple’s and pear’s or I saw two dog’s, or in possessive pronouns such as hers, yours, or theirs. See also its (usage).