/ok'toh sen ten"euh ree, -sen"tn er'ee/ or, esp. Brit., /-sen tee"neuh ree/ , adj., n., pl. octocentenaries .
adj.
1. pertaining to 800 or a period of 800 years; marking the completion of 800 years.
n.
2. an 800th anniversary or its celebration.
[ 1885-90; OCTO- + CENTENARY ]