Source : Webster's Revised Unabridged Dictionary (1913)

Step \Step\, n. [AS. st[ae]pe. See {Step}, v. i.]
   1. An advance or movement made by one removal of the foot; a
      pace.

   2. A rest, or one of a set of rests, for the foot in
      ascending or descending, as a stair, or a round of a
      ladder.

            The breadth of every single step or stair should be
            never less than one foot.             --Sir H.
                                                  Wotton.

   3. The space passed over by one movement of the foot in
      walking or running; as, one step is generally about three
      feet, but may be more or less. Used also figuratively of
      any kind of progress; as, he improved step by step, or by
      steps.

            To derive two or three general principles of motion
            from phenomena, and afterwards to tell us how the
            properties and actions of all corporeal things
            follow from those manifest principles, would be a
            very great step in philosophy.        --Sir I.
                                                  Newton.

   4. A small space or distance; as, it is but a step.

   5. A print of the foot; a footstep; a footprint; track.

   6. Gait; manner of walking; as, the approach of a man is
      often known by his step.

   7. Proceeding; measure; action; an act.

            The reputation of a man depends on the first steps
            he makes in the world.                --Pope.

            Beware of desperate steps. The darkest day, Live
            till to-morrow, will have passed away. --Cowper.

            I have lately taken steps . . . to relieve the old
            gentleman's distresses.               --G. W. Cable.

   8. pl. Walk; passage.

            Conduct my steps to find the fatal tree. --Dryden.

   9. pl. A portable framework of stairs, much used indoors in
      reaching to a high position.

   10. (Naut.) In general, a framing in wood or iron which is
       intended to receive an upright shaft; specif., a block of
       wood, or a solid platform upon the keelson, supporting
       the heel of the mast.

   11. (Mach.)
       (a) One of a series of offsets, or parts, resembling the
           steps of stairs, as one of the series of parts of a
           cone pulley on which the belt runs.
       (b) A bearing in which the lower extremity of a spindle
           or a vertical shaft revolves.

   12. (Mus.) The intervak between two contiguous degrees of the
       csale.

   Note: The word tone is often used as the name of this
         interval; but there is evident incongruity in using
         tone for indicating the interval between tones. As the
         word scale is derived from the Italian scala, a ladder,
         the intervals may well be called steps.

   13. (Kinematics) A change of position effected by a motion of
       translation. --W. K. Clifford.

   {Back step}, {Half step}, etc. See under {Back}, {Half}, etc.
      

   {Step grate}, a form of grate for holding fuel, in which the
      bars rise above one another in the manner of steps.

   {To take steps}, to take action; to move in a matter.



   {Half hitch}, a sailor's knot in a rope; half of a clove
      hitch.

   {Half hose}, short stockings; socks.

   {Half measure}, an imperfect or weak line of action.

   {Half note} (Mus.), a minim, one half of a semibreve.

   {Half pay}, half of the wages or salary; reduced pay; as, an
      officer on half pay.

   {Half price}, half the ordinary price; or a price much
      reduced.

   {Half round}.
      (a) (Arch.) A molding of semicircular section.
      (b) (Mech.) Having one side flat and the other rounded; --
          said of a file.

   {Half shift} (Mus.), a position of the hand, between the open
      position and the first shift, in playing on the violin and
      kindred instruments. See {Shift}.

   {Half step} (Mus.), a semitone; the smallest difference of
      pitch or interval, used in music.

   {Half tide}, the time or state of the tide equally distant
      from ebb and flood.

   {Half time}, half the ordinary time for work or attendance;
      as, the half-time system.

   {Half tint} (Fine Arts), a middle or intermediate tint, as in
      drawing or painting. See {Demitint}.

   {Half truth}, a statement only partially true, or which gives
      only a part of the truth. --Mrs. Browning.

   {Half year}, the space of six months; one term of a school
      when there are two terms in a year.

Source : WordNet®

half step
     n : the musical interval between adjacent keys on a keyboard
         instrument [syn: {semitone}]