Definition of "donjon" [don•jon]

• The fortified main tower of a castle; a keep. (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.

• "It held meetings in our big vault, which they called the donjon keep, and, naturally, when one of them was going on, boys were scarcer around the office than hen's teeth."
• "Although the donjon was a fundamental element of castle design from Norman times, Greenwich had no fortifications, no moat, and no visible sense of being a castle."
• "After passing the donjon, which is situated at the extreme end of the left wing, we went to the back of the chateau."