inversion

/in verr"zheuhn, -sheuhn/, n.

1. an act or instance of inverting.

2. the state of being inverted.

3. anything that is inverted.

4. Rhet. reversal of the usual or natural order of words; anastrophe.

5. Gram. any change from a basic word order or syntactic sequence, as in the placement of a subject after an auxiliary verb in a question or after the verb in an exclamation, as "When will you go?" and "How beautiful is the rose!"

6. Anat., Pathol. the turning inward of a part, as the foot.

7. Chem.

a. a hydrolysis of certain carbohydrates, as cane sugar, that results in a reversal of direction of the rotatory power of the carbohydrate solution, the plane of polarized light being bent from right to left or vice versa.

b. a reaction in which a starting material of one optical configuration forms a product of the opposite configuration.

8. Music.

a. the process or result of transposing the tones of an interval or chord so that the original bass becomes an upper voice.

b. (in counterpoint) the transposition of the upper voice part below the lower, and vice versa.

c. presentation of a melody in contrary motion to its original form.

9. Psychiatry. assumption of the sexual role of the opposite sex; homosexuality.

10. Genetics. a type of chromosomal aberration in which the position of a segment of the chromosome is changed in such a way that the linear order of the genes is reversed. Cf. chromosomal aberration.

11. Phonet. retroflexion (def. 3).

12. Also called atmospheric inversion, temperature inversion. Meteorol. a reversal in the normal temperature lapse rate, the temperature rising with increased elevation instead of falling.

13. Electricity. a converting of direct current into alternating current.

14. Math. the operation of forming the inverse of a point, curve, function, etc.

adj.

15. pertaining to or associated with inversion therapy or the apparatus used in it: inversion boots.

[1545-55; < L inversion- (s. of inversio) a turning in. See INVERSE, -ION]

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▪ chemical reaction

      in chemistry, the spatial rearrangement of atoms or groups of atoms in a dissymmetric molecule, giving rise to a product with a molecular configuration that is a mirror image of that of the original molecule.

      The reaction is usually one in which an atom or a group of atoms in the molecule is replaced by another atom or group. The phenomenon of inversion is sometimes known as Walden inversion, after the German chemist Paul Walden, who discovered it in 1895. The idea that inversion is the stereochemical consequence of a nucleophilic displacement reaction was introduced by the British chemists Sir Christopher Ingold and E.D. Hughes (see substitution reaction).

▪ literature

also called  anastrophe 

      in literary style and rhetoric, the syntactic reversal of the normal order of the words and phrases in a sentence, as, in English, the placing of an adjective after the noun it modifies (“the form divine”), a verb before its subject (“Came the dawn”), or a noun preceding its preposition (“worlds between”). Inversion is most commonly used in poetry in which it may both satisfy the demands of the metre and achieve emphasis:

In Xanadu did Kubla Khan

A stately pleasure dome decree

(from Samuel Taylor Coleridge (Coleridge, Samuel Taylor)'s “Kubla Khan”)

      Inversion used simply for the sake of maintaining a rhyme scheme is considered a literary defect, although it is a common convention in folk ballads:

Then up spoke the captain of our gallant ship,

And a well-spoken man was he;

“I have married a wife in Salem town,

And tonight she a widow will be”

(from “The Mermaid,” anonymous)

▪ music

      in music, rearrangement of the top-to-bottom elements in an interval, a chord, a melody, or a group of contrapuntal lines of music. The inversion of chords and intervals is utilized for various purposes, e.g., to create a melodic bass line or (with certain chords) to modulate to a new key. To invert a chord or an interval is to rearrange its notes so that the original bottom note becomes an upper note; for example,

      An interval (such as c′–f′) and its inversion (f′–c″) are complementary: together they form an octave. A three-note chord (triad) can be inverted twice from its original, or root, position.

      Inversions of melody and counterpoint enable a composer to elaborate on basic musical material; they are common in fugues. To invert a melody means to change its ascending intervals to descending ones and vice versa; for example:

      becomes

      In inverted counterpoint, the original order of the contrapuntal lines is rearranged. In this way a line sounds above the line that it originally sounded beneath; for example,

      becomes

 

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