hydrogen bromide

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun An irritating colorless gas, HBr, used in the manufacture of barbiturates and synthetic hormones.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun inorganic chemistry A colourless gas having an irritating smell; it has the molecular formula HBr, and dissolves in water to form hydrobromic acid; it has many industrial applications including the production of barbiturates and synthetic hormones.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a colorless gas that yields hydrobromic acid in solution with water