Etymology From sesqui- (“one and a half”) + centenary (“100 year anniversary”). Noun sesquicentenary (plural sesquicentenaries) A 150-year anniversary. Related terms sesquicentenarian sesquicentennial Translations a 150 year anniversary German: Hundertfünfzigjahrfeier f, hundertfünfzigjähriges Jubiläum n Russian: полуторавековой юбиле́й m (polutoravekovoj jubiléj), стопятидесятилетие n (stopjatidesjatiletije)