The Collaborative International Dictionary of English v.0.48:

Above \A*bove"\, prep. [OE. above, aboven, abuffe, AS. abufon;
   an (or on) on + be by + ufan upward; cf. Goth. uf under.
   [root]199. See Over.]
   1. In or to a higher place; higher than; on or over the upper
      surface; over; -- opposed to below or beneath.
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            Fowl that may fly above the earth.    --Gen. i. 20.
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   2. Figuratively, higher than; superior to in any respect;
      surpassing; beyond; higher in measure or degree than; as,
      things above comprehension; above mean actions; conduct
      above reproach. "Thy worth . . . is actions above my
      gifts." --Marlowe.
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            I saw in the way a light from heaven above the
            brightness of the sun.                --Acts xxxvi.
                                                  13.
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   3. Surpassing in number or quantity; more than; as, above a
      hundred. (Passing into the adverbial sense. See Above,
      adv., 4.)
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   above all, before every other consideration; chiefly; in
      preference to other things.
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   Over and above, prep. or adv., besides; in addition to.
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WordNet (r) 3.0 (2006):

above all
    adv 1: above and beyond all other consideration; "above all, you
           must be independent" [syn: above all, most
           importantly, most especially]
    2: taking everything together; "she was first and last a
       scientist" [syn: first and last, above all]

Moby Thesaurus II by Grady Ward, 1.0:

23 Moby Thesaurus words for "above all":
   a fortiori, all the more, chiefly, dominantly, especially, even,
   ever so, first of all, in chief, in the main, indeed, mainly,
   more than ever, mostly, never so, no end, particularly, peculiarly,
   predominantly, primarily, principally, still more, yea