The Collaborative International Dictionary of English v.0.48:

Supreme \Su*preme"\, a. [L. supremus, superlative of superus
   that is above, upper, fr. super above: cf. F. supr[^e]me. See
   Super-, and cf. Sum.]
   1. Highest in authority; holding the highest place in
      authority, government, or power.
      [1913 Webster]

            He that is the supreme King of kings. --Shak.
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   2. Highest; greatest; most excellent or most extreme; utmost;
      greatist possible (sometimes in a bad sense); as, supreme
      love; supreme glory; supreme magnanimity; supreme folly.
      [1913 Webster]

            Each would be supreme within its own sphere, and
            those spheres could not but clash.    --De Quincey.
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   3. (Bot.) Situated at the highest part or point.
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   The Supreme, the Almighty; God.
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WordNet (r) 3.0 (2006):

supreme
    adj 1: final or last in your life or progress; "the supreme
           sacrifice"; "the supreme judgment"
    2: greatest in status or authority or power; "a supreme
       tribunal" [syn: sovereign, supreme]
    3: highest in excellence or achievement; "supreme among
       musicians"; "a supreme endxxeavor"; "supreme courage"
    4: greatest or maximal in degree; extreme; "supreme folly"