Compared to the same time period in the previous day.

(idiomatic) For an indefinite number of days.

(idiomatic) Every day; daily; constantly or continuously (especially, of something that has become routine or monotonous).

You learn something new every day.

(education) A day on which an institution (such as a farm or a university) hosts visitors who come to learn about it.

plural of access day

(aviation, military) An aviator (usually a fighter pilot) who destroys five or more enemy aircraft (the number required to become an ace) in a single day.

plural of scambling day

(obsolete) One of the days during Lent when meat was scarce.

(Kenya, colloquial) Friday, seen as the start of the weekend and a time to party.