Source : Webster's Revised Unabridged Dictionary (1913)

Poisonous \Poi"son*ous\, a.
   Having the qualities or effects of poison; venomous; baneful;
   corrupting; noxious. --Shak. -- {Poi"son*ous*ly}, adv. --
   {Poi"son*ous*ness}, n.

Source : WordNet®

poisonously
     adv : in a very malevolent manner [syn: {venomously}]