- pertaining to or marking the completion of a period of 150 years.
- a 150th anniversary or its celebration.
- of or relating to a period of 150 years
- a period or cycle of 150 years
- a 150th anniversary or its celebration
adj.“pertaining to a century and a half,” 1878, from sesqui- + centennial. As a noun from 1880; first recorded reference is to Baltimore’s.