WordReference Random House Unabridged Dictionary of American English © 2025
sem•i•cen•ten•ar•y
(sem′ē sen ten′ə rē, -sen′tn er′ē, sem′ī- or, esp. Brit., -sen tē′nə rē),USA pronunciation adj., n., pl. -ar•ies.
- semicentennial.
- semi- + centenary 1865–70