Source : Webster's Revised Unabridged Dictionary (1913)

   {Prime and ultimate ratio}. (Math.). See {Ultimate}.

   {Prime conductor}. (Elec.) See under {Conductor}.

   {Prime factor} (Arith.), a factor which is a prime number.

   {Prime figure} (Geom.), a figure which can not be divided
      into any other figure more simple than itself, as a
      triangle, a pyramid, etc.

   {Prime meridian} (Astron.), the meridian from which longitude
      is reckoned, as the meridian of Greenwich or Washington.
      

   {Prime minister}, the responsible head of a ministry or
      executive government; applied particularly to that of
      England.

   {Prime mover}. (Mech.)
      (a) A natural agency applied by man to the production of
          power. Especially: Muscular force; the weight and
          motion of fluids, as water and air; heat obtained by
          chemical combination, and applied to produce changes
          in the volume and pressure of steam, air, or other
          fluids; and electricity, obtained by chemical action,
          and applied to produce alternation of magnetic force.
      (b) An engine, or machine, the object of which is to
          receive and modify force and motion as supplied by
          some natural source, and apply them to drive other
          machines; as a water wheel, a water-pressure engine, a
          steam engine, a hot-air engine, etc.
      (c) Fig.: The original or the most effective force in any
          undertaking or work; as, Clarkson was the prime mover
          in English antislavery agitation.

   {Prime number} (Arith.), a number which is exactly divisible
      by no number except itself or unity, as 5, 7, 11.

   {Prime vertical} (Astron.), the vertical circle which passes
      through the east and west points of the horizon.

   {Prime-vertical dial}, a dial in which the shadow is
      projected on the plane of the prime vertical.

   {Prime-vertical transit instrument}, a transit instrument the
      telescope of which revolves in the plane of the prime
      vertical, -- used for observing the transit of stars over
      this circle.

Source : WordNet®

Prime Minister
     n 1: the person who holds the position of head of state in
          England [syn: {PM}, {premier}]
     2: the person who is head of state (in several countries) [syn:
         {chancellor}, {premier}]