sesquicentenary
Concise Oxford English Dictionary © 2008 Oxford University Press:
sesquicentenary /ˌsɛskwɪsɛnˈtiːn(ə)ri, -ˈtɛn-/
▶noun (pl. sesquicentenaries) the one-hundred-and-fiftieth anniversary of a significant event.
– derivatives
sesquicentennial adjective & noun.
sesquicentennial adjective & noun.
'sesquicentenary' also found in these Oxford entries:

