Pervert

The word pervert is pronounced with different stress, according to whether it is a noun or a verb. Both should only be used when the writer is certain that they are appropriate. In ordinary academic writing, they should be avoided.

• The verb 'to pervert' is stressed on the second syllable: 'per-VERT', IPA: /pɜː^r ˈvɜː^rt/. It is derived from the Latin per- "with the sense 'away entirely, to destruction, to the bad'" (OED and vertĕre, 'to turn'. So its general meaning is 'to lead astray', 'to take in a wrong or false direction'.
  • The verbal noun perverting is part of a criminal offence under the common law in England and Wales: that of perverting the course of justice. This is any behaviour, such as threatening or bribing witnesses or jurors, in order to prevent justice and law being properly carried out.
  • It is often used, particularly in the -ed participle perverted (and the associated abstract noun perversion), to mean, as OED puts it (at meaning 1.b.: "Sexual behaviour or preference that is different from the norm; spec. that which is considered to be unacceptable or socially threatening, or to constitute a mental illness; an instance of this." It gives the following usage not (our bold): "From the late 19th cent[ury] until the mid 20th cent[ury], medical and mental health professionals treated homosexuality, along with a number of other sexual tendencies, as a psychological problem. Homosexuality per se was removed from the standard mental health diagnosis manual in the United Kingdom in 1973, and the use of the term perversion to refer to homosexuality is now considered highly offensive."
• The noun 'a pervert' (pronounced with the stress on the first syllable, 'PER-vert', IPA: /ˈpɜː^r vɜː^rt/is now almost always used to cast aspersions on a person's sexuality, although it had a commoner meaning in religion. OED: "A person whose sexual behaviour or inclinations are regarded as abnormal and unacceptable.

The use of the term pervert to refer to a homosexual person is now considered highly offensive."

Note

This pattern of shifting stress in words that look identical but belong to two separate word classes is quite common in English.

Quirk (1985) (Appendix I.56 B) describes the most common: "When verbs of two syllables are converted into nouns, the stress is sometimes shifted from the second to the first syllable. The first syllable, typically a Latin prefix, often has a reduced vowel /ə/ in the verb but a full vowel in the noun: He was con-VICT-ed (IPA: /kən ˈvɪkt ɪd/) of theft, and so became a CON vict (IPA: /ˈkɒn vɪkt/)" [AWE's rendition of IPA].

There follows a list of some 57 "words having end-stress as verbs but initial stress as nouns in Br[itish] E[nglish]." Note that "in Am[erican] E[nglish], many have initial stress as verbs also". Quirk's list is the foundation of AWE's category:shift of stress. Additions have been made from, amongst others, Fowler, 1926-1996.