Definition of "decennial" [de•cen•ni•al]

• Relating to or lasting for ten years. (adjective)
• Occurring every ten years. (adjective)
• A tenth anniversary. (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.

• "Public opinion already recalled the decennial period which separated the existing panic from that of 1873."
• "Since 1790, the U.S. has taken a population snapshot, called the decennial census, every 10 years."
• "An accurate decennial Census is critical to our representative democracy."