A US national holiday celebrated on the second Monday in October, for Christopher Columbus' arrival in the Americas.

A paid personal day intended to be used due to illness either for recuperation or medical treatment.

A day when one is permitted to not attend work in order to attend to personal matters.

A day in summer.

(idiomatic) A difficult period of need, when things do not go right. / Used other than figuratively or idiomatically: see rainy, day.

the next day.

(childish) A contrived holiday on which everything is done backwards, for example "yes" means "no".

For the period of an entire day, or at least during all the daytime of a day.

A Canadian statutory holiday celebrating the country's creation in 1867, celebrated each year on July 1st.

(Britain, historical) December 21st, St. Thomas's Day, a day for begging before Christmas.