Source : Webster's Revised Unabridged Dictionary (1913)

   5. (Chem.) The positive, or non-acid component of a salt; a
      substance which, combined with an acid, neutralizes the
      latter and forms a salt; -- applied also to the hydroxides
      of the positive elements or radicals, and to certain
      organic bodies resembling them in their property of
      forming salts with acids.

   6. (Pharmacy) The chief ingredient in a compound.

   7. (Dyeing) A substance used as a mordant. --Ure.

   8. (Fort.) The exterior side of the polygon, or that
      imaginary line which connects the salient angles of two
      adjacent bastions.

   9. (Geom.) The line or surface constituting that part of a
      figure on which it is supposed to stand.

   10. (Math.) The number from which a mathematical table is
       constructed; as, the base of a system of logarithms.

   11. [See {Base} low.] A low, or deep, sound. (Mus.)
       (a) The lowest part; the deepest male voice.
       (b) One who sings, or the instrument which plays, base.
           [Now commonly written {bass}.]

                 The trebles squeak for fear, the bases roar.
                                                  --Dryden.

   12. (Mil.) A place or tract of country, protected by
       fortifications, or by natural advantages, from which the
       operations of an army proceed, forward movements are
       made, supplies are furnished, etc.

   13. (Mil.) The smallest kind of cannon. [Obs.]

   14. (Zo["o]l.) That part of an organ by which it is attached
       to another more central organ.

   15. (Crystallog.) The basal plane of a crystal.

   16. (Geol.) The ground mass of a rock, especially if not
       distinctly crystalline.

   17. (Her.) The lower part of the field. See {Escutcheon}.

   18. The housing of a horse. [Obs.]

   19. pl. A kind of skirt ( often of velvet or brocade, but
       sometimes of mailed armor) which hung from the middle to
       about the knees, or lower. [Obs.]

   20. The lower part of a robe or petticoat. [Obs.]

   21. An apron. [Obs.] ``Bakers in their linen bases.''
       --Marston.

   22. The point or line from which a start is made; a starting
       place or a goal in various games.

             To their appointed base they went.   --Dryden.

   23. (Surv.) A line in a survey which, being accurately
       determined in length and position, serves as the origin
       from which to compute the distances and positions of any
       points or objects connected with it by a system of
       triangles. --Lyman.

   24. A rustic play; -- called also {prisoner's base}, {prison
       base}, or {bars}. ``To run the country base.'' --Shak.

   25. (Baseball) Any one of the four bounds which mark the
       circuit of the infield.

   {Altern base}. See under {Altern}.

   {Attic base}. (Arch.) See under {Attic}.

   {Base course}. (Arch.)
       (a) The first or lower course of a foundation wall, made
           of large stones of a mass of concrete; -- called also
           {foundation course}.
       (b) The architectural member forming the transition
           between the basement and the wall above.

   {Base hit} (Baseball), a hit, by which the batsman, without
      any error on the part of his opponents, is able to reach
      the first base without being put out.

   {Base line}.
       (a) A main line taken as a base, as in surveying or in
           military operations.
       (b) A line traced round a cannon at the rear of the vent.
           

   {Base plate}, the foundation plate of heavy machinery, as of
      the steam engine; the bed plate.

   {Base ring} (Ordnance), a projecting band of metal around the
      breech, connected with the body of the gun by a concave
      molding. --H. L. Scott.



   {Base hit}, {Safe hit}, {Sacrifice hit}. (Baseball) See under
      {Base}, {Safe}, etc.

Source : WordNet®

base hit
     n : (baseball) the successful act of striking a baseball in such
         a way that the batter reaches base safely [syn: {safety},
          {bingle}]