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.

(medicine) Unable to see clearly in bright light; hemeralopic

Alternative spelling of day-blind

The day of the week/month etc. when wages are issued.

(medicine) The inability to see clearly in bright light; hemeralopia

(US) A day when one is permitted to not attend work in order to go on a vacation or attend to other matters.

One of the dog days of summer: a late-summer day.

One person's working time for a day, or the equivalent, used as a measure of how much work or labor is required or consumed to perform some task.

For a very long or seemingly endless time.