Source : Webster's Revised Unabridged Dictionary (1913)

Vagary \Va*ga"ry\, n.; pl. {Vagaries}. [L. vagari to stroll
   about. See {Vague}.]
   1. A wandering or strolling. [Obs.]

   2. Hence, a wandering of the thoughts; a wild or fanciful
      freak; a whim; a whimsical purpose. ``The vagaries of a
      child.'' --Spectator.

            They changed their minds, Flew off, and into strange
            vagaries fell.                        --Milton.

Source : WordNet®

vagary
     n : an unexpected and inexplicable change in something (in a
         situation or a person's behavior, etc.); "the vagaries of
         the weather"; "his wealth fluctuates with the vagaries of
         the stock market"; "he has dealt with human vagaries for
         many years"