The Collaborative International Dictionary of English v.0.48:

Illaudable \Il*laud"a*ble\, a. [L. illaudabilis. See In- not,
   and Laudable.]
   Not laudable; not praise-worthy; worthy of censure or
   disapprobation. --Milton. -- Il*laud"a*bly, adv. [Obs.]
   --Broome.
   [1913 Webster]