The Collaborative International Dictionary of English v.0.48:

Slim \Slim\ (sl[i^]m), a. [Compar. Slimmer; superl.
   Slimmest.] [Formerly, bad, worthless, weak, slight, awry,
   fr. D. slim; akin to G. schlimm, MHG. slimp oblique, awry; of
   uncertain origin. The meaning of the English word seems to
   have been influenced by slender.]
   1. Worthless; bad. [Prov. Eng. & Scot.]
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   2. Weak; slight; unsubstantial; poor; as, a slim argument.
      "That was a slim excuse." --Barrow.
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   3. Of small diameter or thickness in proportion to the height
      or length; slender; as, a slim person; a slim tree.
      --Grose.
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