berserk Definition

berserk
adj

1. colloq & facetious
Violently angry; crazy.
Thesaurus: crazy, mad, demented, deranged, frenzied, insane, maniacal, rabid, raving, enraged, gone amok; Antonym: calm, sane.

noun

1. historical
A Norse warrior who rushed into battle in a wild frenzied rage.
Form: berserker (also)

Etymology: 19c, originally as a noun: from Norse berserkr, probably from bern a bear + serkr coat.