Source : Webster's Revised Unabridged Dictionary (1913)

Birt \Birt\ (b[~e]rt), n. [OE. byrte; cf. F. bertonneau. Cf.
   {Bret}, {Burt}.] (Zo["o]l.)
   A fish of the turbot kind; the brill. [Written also {burt},
   {bret}, or {brut}.] [Prov. Eng.]