from The American Heritage® Dictionary of the English Language, 4th Edition
- adj. Marking the 50th anniversary of an event.
- n. A 50th anniversary or its celebration.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- adj. Occurring every 50 years
- n. A 50th anniversary.
from the GNU version of the Collaborative International Dictionary of English
- adj. Of or pertaining to half of a century, or a period of fifty years.
- n. A fiftieth anniversary.
from The Century Dictionary and Cyclopedia
- Occurring at the end of, or celebrating the completion of, fifty years, or half a century: as, a semi-centennial celebration.
- n. A semi-centennial celebration.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- adj. of or relating to or marking the 50th anniversary
- n. the 50th anniversary (or the celebration of it)
semi- (“half”) + centennial (“of 100 years”) (Wiktionary)