lunker

lunk·er

L0293000 (lŭng′kər)n. Informal Something, especially a game fish, that is large for its kind.
[Origin unknown.]

lunker

(ˈlʌŋkə) n (Fishing) slang US an exceptionally large fish

lun•ker

(ˈlʌŋ kər)

n. something unusually large for its kind, esp. a large game fish. [1910–15; lunk- (see lunkhead) + -er1]