late Middle English: from Old French plurel or Latin pluralis, from plus, plur- 'more'
1 An apostrophe may be used to form the plural of letters (r’s) and numbers (7's), as well as single words referred to themselves (four the’s in one sentence). It should not be used to form plurals of ordinary nouns: four apples, not four apple’s. 2 The regular plurals of abbreviations and acronyms may be spelled by simply adding an s: CDs, MiGs. They may also, especially if periods are involved, employ an apostrophe: D.D.S.’s. 3 The plurals of proper names typically end in s or es, never with an apostrophe: the Smiths, the Joneses, the Rosses. See also apostrophe1 (usage).