berserk

nouns

one of the ancient Norse warriors legendary for working themselves into a frenzy before a battle and fighting with reckless savagery and insane fury
berserk, berserker

adjectives

frenzied as if possessed by a demon
"the soldier was completely amuck"; "berserk with grief"; "a berserk worker smashing windows"
amok, amuck, berserk, demoniac, demoniacal, possessed