happy hour

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

• noun A period of time, usually in late afternoon and early evening, during which a bar or lounge features drinks at reduced prices.

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

• noun A time of day, usually in the afternoon or early evening, when a bar or pub offers its drinks at a discounted price.
• noun Any small gathering, usually in the afternoon or early evening, set aside to relax and have a drink.

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

• noun the time of day when a bar sells alcoholic drinks at a reduced price