The Collaborative International Dictionary of English v.0.48:

Backward \Back"ward\, Backwards \Back"wards\, adv. [Back, adv. +
   -ward.]
   1. With the back in advance or foremost; as, to ride
      backward.
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   2. Toward the back; toward the rear; as, to throw the arms
      backward.
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   3. On the back, or with the back downward.
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            Thou wilt fall backward.              --Shak.
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   4. Toward, or in, past time or events; ago.
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            Some reigns backward.                 --Locke.
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   5. By way of reflection; reflexively. --Sir J. Davies.
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   6. From a better to a worse state, as from honor to shame,
      from religion to sin.
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            The work went backward.               --Dryden.
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   7. In a contrary or reverse manner, way, or direction;
      contrarily; as, to read backwards.
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            We might have . . . beat them backward home. --Shak.
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WordNet (r) 3.0 (2006):

backwards
    adv 1: at or to or toward the back or rear; "he moved back";
           "tripped when he stepped backward"; "she looked rearward
           out the window of the car" [syn: back, backward,
           backwards, rearward, rearwards] [ant: forrad,
           forrard, forward, forwards, frontward,
           frontwards]
    2: in a manner or order or direction the reverse of normal;
       "it's easy to get the `i' and the `e' backward in words like
       `seize' and `siege'"; "the child put her jersey on backward"
       [syn: backward, backwards]