(biology) A light-dark cycle that has more or less than 24 hours created artificially for testing the rhythms of organisms.

The French national holiday celebrated on 14 July each year. It commemorates the 1790 Fête de la Fédération, held on the first anniversary of the storming of the Bastille on 14 July 1789; the Fête de la Fédération was seen as a symbol of the uprising of the modern French "nation".

Modern, recent.

(Britain) Each of the four days customarily regarded as starting a new quarter year, on which rents etc are often due.

Alternative letter-case form of Anzac Day.

The very beginning. / (US, slang) A close, longtime friend, one who has been around since the beginning.

At the very beginning; when something is entirely new.

Period of calm during the winter, when storms do not occur. / (idiomatic) A period of calm, usually in the past and often nostalgic.

plural of snow day

(UK) A male day pupil.