Source : Webster's Revised Unabridged Dictionary (1913)

Dip \Dip\, n.
   1. The action of dipping or plunging for a moment into a
      liquid. ``The dip of oars in unison.'' --Glover.

   2. Inclination downward; direction below a horizontal line;
      slope; pitch.

   3. A liquid, as a sauce or gravy, served at table with a
      ladle or spoon. [Local, U.S.] --Bartlett.

   4. A dipped candle. [Colloq.] --Marryat.

   {Dip of the horizon} (Astron.), the angular depression of the
      seen or visible horizon below the true or natural horizon;
      the angle at the eye of an observer between a horizontal
      line and a tangent drawn from the eye to the surface of
      the ocean.

   {Dip of the needle}, or {Magnetic dip}, the angle formed, in
      a vertical plane, by a freely suspended magnetic needle,
      or the line of magnetic force, with a horizontal line; --
      called also {inclination}.

   {Dip of a stratum} (Geol.), its greatest angle of inclination
      to the horizon, or that of a line perpendicular to its
      direction or strike; -- called also the {pitch}.

Source : WordNet®

magnetic dip
     n : (physics) the angle that a magnetic needle makes with the
         plane of the horizon [syn: {dip}, {angle of dip}, {magnetic
         inclination}, {inclination}]