Source : Webster's Revised Unabridged Dictionary (1913)

Centripetal \Cen*trip"e*tal\, a. [L. centrum center + petere to
   move toward.]
   1. Tending, or causing, to approach the center.

   2. (Bot.)
      (a) Expanding first at the base of the inflorescence, and
          proceeding in order towards the summit.
      (b) Having the radicle turned toward the axis of the
          fruit, as some embryos.

   3. Progressing by changes from the exterior of a thing toward
      its center; as, the centripetal calcification of a bone.
      --R. Owen.

   {Centripetal force} (Mech.), a force whose direction is
      towards a center, as in case of a planet revolving round
      the sun, the center of the system, See {Centrifugal
      force}, under {Centrifugal}.

   {Centripetal impression} (Physiol.), an impression (sensory)
      transmitted by an afferent nerve from the exterior of the
      body inwards, to the central organ.

Source : WordNet®

centripetal
     adj 1: tending to move toward a center; "centripetal force" [ant: {centrifugal}]
     2: tending to unify [syn: {unifying(a)}]
     3: of a nerve fiber or impulse originating outside and passing
        toward the central nervous system; "sensory neurons" [syn:
         {receptive}, {sensory(a)}]