Hyperbaton is figure of speech in which words in an sentence are not in their expected order. It is classified as a figure of disorder and often is used to emphasize a particular word or phrase. In English its effect can be quite startling or occasionally confusing, but in a highly inflected language such as Latin it is far more common.
Like other figures of disorder, hyperbaton interrupts the expected flow of a sentence. In English, for instance, it is common for a sentence to have the basic word order subject-verb-direct object, as in, "Michael ate the fish." If it is rearranged as "Michael the fish ate," which has subject-direct object-verb word order, the sentence draws greater attention to itself. The word or phrase that is out of order is particularly emphasized — in this case, "the fish." The point of the hyperbaton in this example might be to emphasize that Michael ate the fish, as opposed to the chicken or the beef or the vegetables.
In metered or rhyming poetry, hyperbaton is sometimes employed to make a sentence fit into the poem's structure. When done poorly, this can result in clumsy phrasing, but when done well it may also add emphasis in desired places. Shakespeare does this in Othello when he writes, "Nor scar that whiter skin of hers than snow," instead of the expected, "Nor scar her skin that is whiter than snow." The purpose of the hyperbaton here is twofold. On the one hand it makes the line fit into iambic pentameter, but it also moves the word "whiter" closer the beginning of the line for emphasis.
Hyperbaton can be used much more naturally with inflected languages, which tend to have more flexible word order than English. In Latin, for example, the most common sentence structure is subject-direct object-verb. So much grammatical information is stored in the endings of the words themselves that this order can be changed more easily without undue confusion. This would place a mild emphasis on the word that comes first, much as an English speaker might change his or her inflection slightly for emphasis.
There are a number of closely related literary terms that refer to specific types of hyperbaton. Anastrophe, for instance, is sometimes used interchangeably with hyperbaton, but anastrophe more technically refers to moving only one word out of its expected syntax rather than an entire phrase. Hysterologia is a form of hyperbaton where a word or phrase is inserted between a preposition and its object.