From Longman Dictionary of Contemporary Englishberserkber‧serk /bɜːˈsɜːk, bə- $ bɜːrˈsɜːrk, ˈbɜːrsɜːrk/ adjective → go berserk
Examples from the Corpus
berserk• But how can our uppermost tier go so berserk?• Toos threw unending series of berserk punches, ignoring incoming rounds as if they were raindrops on a pleasant spring day.Origin berserk (1800-1900) Old Norse berserkr “wild fighter”, from björn “bear” + serkr “shirt” 