The Collaborative International Dictionary
sun bittern
Bittern \Bit"tern\, n. [OE. bitoure, betore, bitter, fr. F. butor; of unknown origin.] (Zo["o]l.) A wading bird of the genus Botaurus, allied to the herons, of various species.
Note: The common European bittern is Botaurus stellaris. It makes, during the brooding season, a noise called by Dryden bumping, and by Goldsmith booming. The American bittern is Botaurus lentiginosus, and is also called stake-driver and meadow hen. See Stake-driver.
Note: The name is applied to other related birds, as the least bittern ( Ardetta exilis), and the sun bittern.
Wiktionary
sun bittern
n. (alternative spelling of sunbittern English)