1977, from sick (adj.) in the mental sense + ending as in weirdo. Sickie "a pervert" is attested from 1972; sicknik (1959) "pervert, obscene comedian" (applied to Lenny Bruce) has fad ending -nik.
sickening
sickish
sickle
sickly
sickness
sicko
siddha
side
side effect
sidearm
sidearms
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