Apostrophe is an instance in which the speaker of a poem addresses a person who is not present or an inanimate object. This term is not to be confused with the punctuation mark (also called an "apostrophe"), which can be used either to show possession or the contraction of two words. The literary device known as "apostrophe" (which usually doesn't have an article in front of it) refers to a distinct feature of literature (usually a poem, though apostrophe is also possible in prose). Some examples of apostrophe are quite common.

A famous example of apostrophe is the familiar nursery rhyme that begins, "twinkle, twinkle, little star." The specific line which features apostrophe is "how I wonder what you are." The giveaway that apostrophe is being used is the second person pronoun, "you." The speaker here is not only discussing the star, but addressing it.

An equally familiar Christmas carol contains an example of apostrophe: "Oh Christmas tree, Oh Christmas tree, how lovely are thy branches" (emphasis added). Here, "thy" is an old-fashioned word for "your." Apostrophe may address a person who is absent (e.g., Shakespeare's "Wherefore art thou, Romeo?") or dead (e.g., Walt Whitman's, "Oh captain, my Captain!"). Hints that apostrophe may be present are the interjection "oh" and any form of the second-person pronoun ("you," "your," or "thou," "thy", and "thee").