资料来源 : Webster's Revised Unabridged Dictionary (1913)

   {Foul anchor}. (Naut.) See under {Anchor}.

   {Foul ball} (Baseball), a ball that first strikes the ground
      outside of the foul ball lines, or rolls outside of
      certain limits.

   {Foul ball lines} (Baseball), lines from the home base,
      through the first and third bases, to the boundary of the
      field.

   {Foul berth} (Naut.), a berth in which a ship is in danger of
      fouling another vesel.

   {Foul bill}, or {Foul bill of health}, a certificate, duly
      authenticated, that a ship has come from a place where a
      contagious disorder prevails, or that some of the crew are
      infected.

   {Foul copy}, a rough draught, with erasures and corrections;
      -- opposed to fair or clean copy. ``Some writers boast of
      negligence, and others would be ashamed to show their foul
      copies.'' --Cowper.

   {Foul proof}, an uncorrected proof; a proof containing an
      excessive quantity of errors.

   {Foul strike} (Baseball), a strike by the batsman when any
      part of his person is outside of the lines of his
      position.

   {To fall foul}, to fall out; to quarrel. [Obs.] ``If they be
      any ways offended, they fall foul.'' --Burton.

   {To} {fall, or run}, {foul of}. See under {Fall}.

   {To make foul water}, to sail in such shallow water that the
      ship's keel stirs the mud at the bottom.

资料来源 : WordNet®

foul ball
     n : (baseball) a ball struck with the bat so that it does not
         stay between the lines (the foul lines) that define the
         width of the playing field [ant: {fair ball}]