BANEFUL
baleful, baneful
(adjective) deadly or sinister; “the Florida eagles have a fierce baleful look”
baneful, deadly, pernicious, pestilent
(adjective) exceedingly harmful
Source: WordNet® 3.1
Etymology
Adjective
baneful (comparative more baneful, superlative most baneful)
(archaic) Poisonous, deadly.
Harmful, injurious.
Synonyms
• fatal
• mortal
Antonyms
• helpful
• productive
Source: Wiktionary
Bane"ful, a.
Definition: Having poisonous qualities; deadly; destructive; injurious;
noxious; pernicious. "Baneful hemlock." Garth. "Baneful wrath."
Chapman.
– Bane"ful*ly, adv. --Bane"ful*ness, n.
Source: Webster’s Unabridged Dictionary 1913 Edition