Slowing

from WordNet (r) 3.0 (2006)

slowing
    n 1: a decrease in rate of change; "the deceleration of the arms
         race" [syn: {deceleration}, {slowing}, {retardation}] [ant:
         {acceleration}]

from The Collaborative International Dictionary of English v.0.48

Slow \Slow\, v. t. [imp. & p. p. {Slowed}; p. pr. & vb. n.
   {Slowing}.]
   To render slow; to slacken the speed of; to retard; to delay;
   as, to slow a steamer. --Shak.
   [1913 Webster]