An outer room that opens into another room, often used as a waiting room.(noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "anteroom" in a sentence
"This peaceful little oasis of piety and good will might be described as an anteroom of heaven."
"Over here on this wall of the anteroom is the second door."
"The anteroom was a small place fitted up like a parlor, at the side of the stage and on a level with it."