unexpectedly

from WordNet (r) 3.0 (2006)

unexpectedly
    adv 1: in a way that was not expected; "her brother showed up at
           the wedding out of the blue" [syn: {unexpectedly}, {out
           of the blue}]
    2: without advance planning; "they met accidentally" [syn: {by
       chance}, {accidentally}, {circumstantially}, {unexpectedly}]
       [ant: {advisedly}, {by choice}, {by design}, {deliberately},
       {designedly}, {intentionally}, {on purpose}, {purposely}]

from The Collaborative International Dictionary of English v.0.48

Unexpected \Un`ex*pect"ed\, a.
   Not expected; coming without warning; sudden. --
   {Un`ex*pect"ed*ly}, adv. -- {Un`ex*pect"ed*ness}, n.
   [1913 Webster]