semicentenary

[ sem-ee-sen-ten-uh-ree, -sen-tn-er-ee, sem-ahy- or, esp. British, -sen-tee-nuh-ree ]
/ ˌsɛm i sɛnˈtɛn ə ri, -ˈsɛn tnˌɛr i, ˌsɛm aɪ- or, esp. British, -sɛnˈti nə ri /

adjective, noun, plural sem·i·cen·ten·ar·ies.

Origin of semicentenary

First recorded in 1865–70; semi- + centenary