The Collaborative International Dictionary of English v.0.48:

Span \Span\, n. [AS. spann; akin to D. span, OHG. spanna, G.
   spanne, Icel. sp["o]nn. [root]170. See Span, v. t. ]
   1. The space from the thumb to the end of the little finger
      when extended; nine inches; eighth of a fathom.
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   2. Hence, a small space or a brief portion of time.
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            Yet not to earth's contracted span
            Thy goodness let me bound.            --Pope.
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            Life's but a span; I'll every inch enjoy.
                                                  --Farquhar.
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   3. The spread or extent of an arch between its abutments, or
      of a beam, girder, truss, roof, bridge, or the like,
      between its supports.
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   4. (Naut.) A rope having its ends made fast so that a
      purchase can be hooked to the bight; also, a rope made
      fast in the center so that both ends can be used.
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   5. [Cf. D. span, Sw. spann, Dan. spaend, G. gespann. See
      Span, v. t. ] A pair of horses or other animals driven
      together; usually, such a pair of horses when similar in
      color, form, and action.
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   Span blocks (Naut.), blocks at the topmast and
      topgallant-mast heads, for the studding-sail halyards.

   Span counter, an old English child's game, in which one
      throws a counter on the ground, and another tries to hit
      it with his counter, or to get his counter so near it that
      he can span the space between them, and touch both the
      counters. --Halliwell. "Henry V., in whose time boys went
      to span counter for French crowns." --Shak.

   Span iron (Naut.), a special kind of harpoon, usually
      secured just below the gunwale of a whaleboat.

   Span roof, a common roof, having two slopes and one ridge,
      with eaves on both sides. --Gwilt.

   Span shackle (Naut.), a large bolt driven through the
      forecastle deck, with a triangular shackle in the head to
      receive the heel of the old-fashioned fish davit. --Ham.
      Nav. Encyc.
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