noundialect Scottish, British
The European bittern, Botaurus stellaris. Later also (US): the American bittern, B. lentiginosus.
Late Middle English; earliest use found in John Trevisa (c1342–?1402), translator. Origin uncertain; probably an alteration of Old English rāradumbla (masculine), rāredumle (feminine) bittern, with substitution of mire for the first element.