(grammar) A variety of the third person sometimes used for indefinite referents, such as one, as in one shouldn't do that.

(performing arts, idiomatic) The imaginary invisible wall at the front of the stage in a proscenium theatre, through which the audience sees the action in the world of the play.

(anatomy) A fork-shaped structure, specifically the fold of skin where the labia minora meet above the perineum (the frenulum labiorum pudendi).

a form of the Scottish highland dance in which groups of four dancers alternate between solo steps facing one another and a figure-of-eight style with intertwining progressive movement.

A group of four, a quartet or a game (such as golf) played by four players, especially by two teams of two. / A sex act between four people.

The number one thousand four hundred. / The year 1400. / The start of the fifteenth hour of the day on the 24-hour clock i.e. 14:00.

(soccer) The official who keeps things at the dugout in order, and displays substitutions and the amount of injury time

The national holiday of Independence Day in the United States, celebrated on the fourth day in July to mark the anniversary of the signing of the Declaration of Independence from Great Britain in 1776.

(chiefly US) A cocktail containing one part grenadine syrup, one part vodka, and one part blue curaçao, reminiscent of the red, white, and blue colours of the United States flag, often poured in layers so that the colours do not mix when the drink is served.

Having four equal sides; square. / (by extension) Solid, robust. / (cryptography) Pertaining to a four-square cipher. / Pertaining to the International Church of the Foursquare Gospel.