You’re probably familiar with the verb alter, meaning "to make or become different," and you may not be surprised to learn that it is a relative of "alterity." Both words descend from the Latin word alter, meaning "other (of two)." That Latin alter, in turn, comes from a prehistoric Indo-European word that is also an ancestor of our "alien." "Alterity" has been used in English as a fancy word for "otherness" ("the state of being other") since at least 1642. It remains less common than "otherness" and tends to turn up most often in the context of literary theory or cultural studies.
