Definition of quasquicentennial in English:

quasquicentennial

noun

US
  • A one-hundred-and-twenty-fifth anniversary.

adjective

US
  • Of or commemorating a one-hundred-and-twenty-fifth anniversary.

Origin

1960s; earliest use found in The New York Times Book Review. Irregularly from qua- + -squicentennial, the intended sense being ‘a centennial plus a quarter’.

Pronunciation

quasquicentennial

/ˌkwɒskwɪsɛnˈtɛnɪəl/