[1] : The Collaborative International Dictionary of English v.0.48

acceleration \accel`era"tion\, n. l. acceleratio: cf. f.
   acc'el'eration.
   the act of accelerating, or the state of being accelerated;
   increase of motion or action; as, a falling body moves toward
   the earth with an acceleration of velocity; -- opposed to
   retardation.
   1913 webster

         a period of social improvement, or of intellectual
         advancement, contains within itself a principle of
         acceleration.                            --i. taylor.
   1913 webster astr.  physics.

   acceleration of the moon, the increase of the moon's mean
      motion in its orbit, in consequence of which its period of
      revolution is now shorter than in ancient times.

   acceleration and retardation of the tides. see priming
      of the tides, under priming.

   diurnal acceleration of the fixed stars, the amount by
      which their apparent diurnal motion exceeds that of the
      sun, in consequence of which they daily come to the
      meridian of any place about three minutes fifty-six
      seconds of solar time earlier than on the day preceding.
      

   acceleration of the planets, the increasing velocity of
      their motion, in proceeding from the apogee to the perigee
      of their orbits.
      1913 webster
see also:
retardation acceleration of the moon acceleration retardation of the tides priming of the tides priming 
diurnal acceleration of the fixed stars acceleration of the planets 

Planets >> P Words
Planets, definition of term: Planets
planets_pag1.html

Acceleration >> A Words
Acceleration, definition of term: Acceleration
acceleration_pag1.html