Word Origin & History
"Norse warrior," 1822, introduced by Sir Walter Scott, from O.N. berserkr (n.) "raging warrior of superhuman strength," probably from *ber- "bear" + serkr "shirt," thus lit. "a warrior clothed in bearskin." The -r was O.N. masc. singular ending, mistaken for agent noun suffix. The adj. is 1867, from
such phrases as go berserk.
alt. form of berserk
(q.v.), from O.N. berserkr, acc. of berserk. This is the oldest form of the word in its revival in Mod.Eng. (1822), and perhaps Scott, who introduced it, mistook the -r for an agent-noun suffix.