double date

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

• noun A date in which two couples participate.

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

• noun Two couples going on a (romantic) date together.
• verb To go on a double date.

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

• noun a date in which two couples participate