Source : Webster's Revised Unabridged Dictionary (1913)

Freakish \Freak"ish\, a.
   Apt to change the mind suddenly; whimsical; capricious.

         It may be a question whether the wife or the woman was
         the more freakish of the two.            --L'Estrange.

         Freakish when well, and fretful when she's sick.
                                                  --Pope.
   -- {Freak"ish*ly}, adv. -- {Freak"ish*ness}, n.

Source : WordNet®

freakishness
     n : marked strangeness as a consequence of being abnormal [syn:
         {abnormality}]