sesquicentennial[-sen ten′ē əl, -ten′yəl]
sesquicentennial definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
of or ending a period of 150 years
a 150th anniversary or its commemoration
sesquicentennial definition by American Heritage Dictionary
Of or relating to a period of 150 years.noun
A 150th anniversary or its celebration.