Invert

The pronunciation of the word invert varies according to word class.

• The adjective invert has the stress on the first syllable: 'IN-vert', IPA: /ˈɪn vÉœ^rt/. This is mostly a technical term in Chemistry.
• The noun 'an invert' also has the stress on the first syllable: 'IN-vert', IPA: /ˈɪn vÉœ^rt/. This is also a technical term, used in Engineering (to mean an 'upturned arch') and Psychology, where it is no longer a common term, to mean 'a [usually male] homosexual'. "The inverts (a word preferred by homosexuals to perverts) attempt to win converts" (R. Reisner (1974) Graffiti viii. 115, cited in OED.
• The verb 'to invert' has the stress on the second syllable: 'in-VERT', IPA: /ɪn ˈvÉœ^rt/. This is the commonest of the three. Its general meaning is 'to turn upside down', or 'to change the relative position of'; it has further technical senses in such subjects as Music, Information Technology and Mathematics. Rarely, it can mean 'to turn inwards', a meaning to be found in Medicine, and which contributed to the earl;y us in Psychology to mean 'having homosexual feelings', as in "Sexual inversion - that is, the turning-in of the sex instinct towards individuals of the same sex" (Godfrey, J. A. (1901) Sci. Sex v. 206, cited in OED).

Etymological note:Invert, in all word classes, is formed from Latin in-, 'in' or 'on', or 'towards'; + vert[Ä“re], 'to turn'.

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.