illegible

from WordNet (r) 3.0 (2006)

illegible
    adj 1: (of handwriting, print, etc.) not legible; "illegible
           handwriting" [ant: {legible}]

from The Collaborative International Dictionary of English v.0.48

Illegible \Il*leg"i*ble\, a.
   Incapable of being read; not legible; as, illegible
   handwriting; an illegible inscription. --
   {Il*leg"i*ble*ness}, n. -- {Il*leg"i*bly}, adv.
   [1913 Webster]