The Collaborative International Dictionary of English v.0.48:

Lean \Lean\ (l[=e]n), a. [Compar. Leaner (l[=e]n"[~e]r);
   superl. Leanest.] [OE. lene, AS. hl[=ae]ne; prob. akin to
   E. lean to incline. See Lean, v. i. ]
   1. Wanting flesh; destitute of or deficient in fat; slim; not
      plump; slender; meager; thin; lank; as, a lean body; a
      lean cattle.
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   2. Wanting fullness, richness, sufficiency, or
      productiveness; deficient in quality or contents; slender;
      scant; barren; bare; mean; -- used literally and
      figuratively; as, the lean harvest; a lean purse; a lean
      discourse; lean wages. "No lean wardrobe." --Shak.
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            Their lean and flashy songs.          --Milton.
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            What the land is, whether it be fat or lean. --Num.
                                                  xiii. 20.
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            Out of my lean and low ability
            I'll lend you something.              --Shak.
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   3. (Typog.) Of a character which prevents the compositor from
      earning the usual wages; -- opposed to fat; as, lean
      copy, matter, or type.
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   Syn: slender; spare; thin; meager; lank; skinny; gaunt.
        [1913 Webster]

WordNet (r) 3.0 (2006):

leaner
    n 1: (horseshoes) the throw of a horseshoe so as to lean against
         (but not encircle) the stake