1911 Encyclopædia Britannica/Apostrophe
APOSTROPHE (Gr. ἀποστροφή, turning away; the final e being sounded), the name given to an exclamatory rhetorical figure of speech, when a speaker or writer breaks off and addresses some one directly in the vocative. The same word (representing, through the French, the Greek ἀπόστροφος προσῳδία, the accent of elision) means also the sign (’) for the omission of a letter or letters, e.g. in “don’t.” In physiology, “apostrophe” is used more precisely in connexion with its literal meaning of “turning away,” e.g. for movement away from the light, in the case of the accumulation of chlorophyll-corpuscles on the cells of leaves.