Definition of "whatchamacallit" [whatchamacallit]

• Something whose name has been forgotten or is not known. (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.

• "November 7, 2008 at 4: 11 pm cayenne, I retrieved the old masthead / leaderboard / title whatchamacallit from the internet archives."
• "Hey, is it my imagination, or is our masthead / leaderboard / title whatchamacallit reverting to the old format?"
• "But how about this whatchamacallit that the Miami Marlins will have at their new stadium?"