bittern

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Any of several wading birds of the genera Botaurus and Ixobrychus, having mottled brownish plumage and a deep booming cry in the male.
2. n. The bitter water solution of bromides, magnesium, and calcium salts remaining after sodium chloride is crystallized out of seawater.

Century Dictionary and Cyclopedia

1. n. A European wading bird, of the family Ardeidæ and subfamily Botaurinæ; the Botaurus stellaris, a kind of heron. It is about 2 feet long, is speckled, mottled, and freckled with several shades of blackish-brown, buff, etc., lives solitary in bogs and morasses, has a hollow guttural cry, and nests usually on the ground.
2. n. Any heron of the subfamily Botaurinæ. The American bittern is Botaurus mugitans or B. lentiginosus. The very small rail-like herons of the genera Ardetta, Ardeola, etc., are called little or least bitterns; the European species is Ardetta minuta: the North American, A. exilis; and there are others. The tiger bitterns are beautifully striped species of the genus Tigrisoma, as T. brasiliensis.
3. n. In salt-works, the brine remaining after the salt is concreted. This, after being ladled off and the salt taken out of the pan, is returned, and, being again boiled, yields more salt. It is used in the preparation of Epsom salt (the sulphate of magnesia) and Glauber salt (the sulphate of soda), and contains also chlorid of magnesium, and iodine and bromine.
4. n. A very bitter compound of quassia, cocculus indicus, licorice, tobacco, etc., used for adulterating beer. Also called bittering.

Wiktionary

1. n. The liquor remaining after halite (common salt) has been harvested from saline water (brine).
2. n. archaic A very bitter compound of quassia, cocculus indicus, etc., used by fraudulent brewers in adulterating beer.
3. n. Several bird species in the heron family Ardeidae.
4. n. One species tending to have a relatively short neck in comparison with the other members of the family.

GNU Webster's 1913

1. n. (Zoöl.) A wading bird of the genus Botaurus, allied to the herons, of various species.
2. n. The brine which remains in salt works after the salt is concreted, having a bitter taste from the chloride of magnesium which it contains.
3. n. A very bitter compound of quassia, cocculus Indicus, etc., used by fraudulent brewers in adulterating beer.

WordNet 3.0

1. n. relatively small compact tawny-brown heron with nocturnal habits and a booming cry; found in marshes