also skellum, "a rascal, scamp, scoundrel," 1610s, from Dutch schelm, from German schelm "rascal, devil, pestilence, etc.," from Old High German scelmo. Used by Dryden, but "Now arch. (except in S.Africa)" [OED].
*skei-
skein
*skel-
skeletal
skeleton
skelm
skene
skep
skeptic
skeptical
skepticism