Source : Webster's Revised Unabridged Dictionary (1913)

Unwonted \Un*wont"ed\, a.
   1. Not wonted; unaccustomed; unused; not made familiar by
      practice; as, a child unwonted to strangers. --Milton.

   2. Uncommon; unusual; infrequent; rare; as, unwonted changes.
      ``Unwonted lights.'' --Byron. -- {Un*wont"ed*ly}, adv. --
      {Un*wont"ed*ness}, n.

Source : WordNet®

unwontedly
     adv : in an unusual manner