Perv

google

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1940s (originally Australian): abbreviation of the noun pervert.

wiktionary

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Clipping of pervert.

etymonline

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perv (n.)

also perve, "a sexual pervert," 1944, slang shortening of (sexual) pervert (n.). As a slang verb, by 1941 as "to act erotically" (intransitive), by 1959 as "to eroticize" something (transitive).