Noun

1. The move of one pitch in an interval up or down an octave.
2. The reversal of an interval.
3. The reversal of the pitch contour.
4. The reversal of a pitch class succesion, such as a contrapuntal line or melody.
5. The subtraction of pitch classes in a set from twelve, which maps intervals onto their complements with respect to 0, and preserves interval classes, symbolized IX (X being the transposition that is inverted.).
7. a segment of DNA in the context of a chromosome that is reversed in orientation relative to a reference karyotype or genome
8. An increase of air temperature with increase in altitude (the ground being colder than the surrounding air). When an inversion exists, there are no convection currents and wind speeds are below 5 knots. The atmosphere is stable and normally is considered the most favorable state for ground release of chemical agents.
9. Deviation from standard word order by putting the predicate before the subject. It takes place in questions with auxiliary verbs and in normal, affirmative clauses beginning with a negative particle, for the purpose of emphasis.

   (with an auxiliary verb) Inversion takes place in the sentence 'Is she here?' — 'is', the predicate, is before 'she', the subject.

   (for the purpose of emphasis) Inversion takes place in the sentence 'Never have I done that.' — 'have', the predicate, is before 'I', the subject, due to 'never' being the first word of the sentence.

10. an outdated term for homosexuality, particularly popular in early psychoanalysis