The Collaborative International Dictionary of English v.0.48:

Athwart \A*thwart"\, prep. [Pref. a- + thwart.]
   1. Across; from side to side of.
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            Athwart the thicket lone.             --Tennyson.
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   2. (Naut.) Across the direction or course of; as, a fleet
      standing athwart our course.
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   Athwart hawse, across the stem of another vessel, whether
      in contact or at a small distance.

   Athwart ships, across the ship from side to side, or in
      that direction; -- opposed to fore and aft.
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