noun

1. an inverting or being inverted
2. something inverted; reversal
3. Chem.
   1. a chemical change in which an optically active substance is converted into another substance having no effect, or the opposite rotatory effects, on the plane of polarization
   2. the conversion of an isomeric compound to its opposite
4. Gram., Rhetoric a reversal of the normal order of words in a sentence (Ex.: “said he” for “he said”)
5. Math.
   1. the process of using an opposite rule or method
   2. an interchange of the terms of a ratio
6. Meteorol. an atmospheric condition in which the normal properties of layers of air are reversed; esp., a temperature reversal in which a layer of warm air traps cooler air near the surface of the earth, preventing the normal rising of surface air
7. Music
   1. the reversal of the position of the tones in an interval or chord, as by raising the lower tone by an octave, etc.
   2. the recurrence of a theme, fugue subject, motive, or figure in identical intervals and note values, but consistently in the opposite direction
8. Phonet. a position of the tongue in which the tip is turned upward and backward
9. Psychiatry homosexuality: now seldom used

Etymology: L inversio < inversus, pp. of invertere