Apostrophe  n. 1 punctuation mark (') indicating: a omission of letters or numbers (e.g. Can't; may '92). B possessive case (e.g. Harry's book; boys' coats). 2 exclamatory passage addressed to (an often absent) person or thing.  apostrophize v. (also -ise) (-zing or -sing) (in sense 2). [greek, = turning away]