Etymology
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skag (n.)

"heroin," 1967, American English, earlier "cigarette" (1915), of unknown origin.

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skank (n.)

"unattractive woman," 1965, perhaps from skag in this sense (1920s), which is of unknown origin.

The verb meaning "dance to reggae music" is from 1976, probably not the same word but also of unknown origin. Related: Skanking.

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