The Collaborative International Dictionary of English v.0.48:

Hull \Hull\, n. [OE. hul, hol, shell, husk, AS. hulu; akin to G.
   h["u]lle covering, husk, case, h["u]llen to cover, Goth.
   huljan to cover, AS. helan to hele, conceal. [root]17. See
   Hele, v. t., Hell.]
   1. The outer covering of anything, particularly of a nut or
      of grain; the outer skin of a kernel; the husk.
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   2. [In this sense perh. influenced by D. hol hold of a ship,
      E. hold.] (Naut.) The frame or body of a vessel, exclusive
      of her masts, yards, sails, and rigging.
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            Deep in their hulls our deadly bullets light.
                                                  --Dryden.
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   Hull down, said of a ship so distant that her hull is
      concealed by the convexity of the sea.
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