Source : Webster's Revised Unabridged Dictionary (1913)

Unwilling \Un*will"ing\, a.
   Not willing; loath; disinclined; reluctant; as, an unwilling
   servant.

         And drop at last, but in unwilling ears, This saving
         counsel, ``Keep your piece nine years.'' --Pope.
   -- {Un*will"ing*ly}, adv. -- {Un*will"ing*ness}, n.

Source : WordNet®

unwillingly
     adv : in an unwilling manner; "he had sinned against her
           unwillingly" [ant: {willingly}]