octocentenary

[ok-toh-sen-ten-uh-ree, -sen-tn-er-ee or, esp. British, -sen-tee-nuh-ree]
noun, plural oc·to·cen·ten·ar·ies.
  1. an 800th anniversary or its celebration.

Origin of octocentenary

First recorded in 1885–90; octo- + centenary
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for octocentenary

octocentenary

noun plural -naries
  1. an eight-hundredth anniversary
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012