'Baneful' definitions:

Definition of 'baneful'

From: WordNet
adjective
Exceedingly harmful [syn: baneful, deadly, pernicious, pestilent]
adjective
Deadly or sinister; "the Florida eagles have a fierce baleful look" [syn: baleful, baneful]

Definition of 'Baneful'

From: GCIDE
  • Baneful \Bane"ful\, a. Having poisonous qualities; deadly; destructive; injurious; noxious; pernicious. "Baneful hemlock." --Garth. "Baneful wrath." --Chapman. [1913 Webster] -- {Bane"ful*ly}, adv. --{Bane"ful*ness}, n. [1913 Webster]