The husband (or man of similar rank) of a chief executive of a nation; especially the husband of the President of a country. / (US) The husband of a governor or mayor.

(Christianity, Quakerism) Sunday (the first day of the Judeo-Christian seven day week)

plural of first grader

(US, education) A pupil who is in first grade.

(generic) A man that is or was a spouse of the political chief executive, when speaking non-specifically.

(generic) A nuclear family that is or was a First Family, when speaking non-specifically.

Used other than figuratively or idiomatically: see first, night. / The first public performance of a play or other show, normally assumed to be held in the evening. / The first night after marriage.

In the UK and various other countries, the initial presentation or announcement of a bill (proposed legislation) to a parliament or legislature, or chamber thereof. In the UK, this takes place without debate and is followed by the publication of the bill for members to examine prior to the second reading.

Synonym of First World War (“World War I”)

(rail transport, also used adverbially) Of a steam locomotive with a tender (a tender locomotive), when it is operating in reverse, with the tender leading.