English Etymology From semi- (“half”) + centenary (“100th anniversary”), q.v. Pronunciation (General American) IPA(key): /ˌsɛˌmaɪˌsɛnˈtɛnəri/, /ˌsɛˌmaɪˈsɛnəˌnɛri/, /ˌsɛˌmaɪˈsɛntəˌnɛri/, /ˌsɛmiˌsɛnˈtɛnəri/, /ˌsɛmiˈsɛnəˌnɛri/, /ˌsɛmiˈsɛntəˌnɛri/ (Received Pronunciation) IPA(key): /ˌsɛmɪsɛnˈtiːnri/, /ˌsɛmɪsɛnˈtiːnəri/, /ˌsɛmɪsɛnˈtɛnri/, /ˌsɛmɪsɛnˈtɛnəri/, /ˌsɛmɪsnˈtiːnri/, /ˌsɛmɪsənˈtiːnri/, /ˌsɛmɪsnˈtiːnəri/, /ˌsɛmɪsənˈtiːnəri/, /ˌsɛmɪsnˈtɛnri/, /ˌsɛmɪsənˈtɛnri/, /ˌsɛmɪsnˈtɛnəri/, /ˌsɛmɪsənˈtɛnəri/ Noun semicentenary (plural semicentenaries) Synonym of semicentennial: a 50th anniversary. The city celebrated its semicentenary last year. Derived terms semicentenarian References “semi-, prefix”, in OED Online , Oxford: Oxford University Press, 2022. Wikiwand - on Seamless Wikipedia browsing. On steroids.