semicentennial

[sem-ee-sen-ten-ee-uh l, sem-ahy-]

adjective

of or relating to a fiftieth anniversary.

noun

a fiftieth anniversary.
the celebration of this anniversary.

Origin of semicentennial

First recorded in 1855–60; semi- + centennial
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for semicentennial

semicentennial

adjective

(prenominal) of or relating to the 50th anniversary of some event
occurring once every 50 years

noun

a 50th 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