An act or instance of making or becoming open.

A gap permitting passage through.

An act or instance of beginning.

A beginning, such as the first performance of a show, the initial period of an art exhibition, the first few measures of a musical composition, or the first few moves in a game.

A noun "opening" represents a vacant position, especially in an array, a time available in a schedule, or an unoccupied employment position.

An opportunity, as in a competitive activity.

(mathematics) In mathematical morphology, the dilation of the erosion of a set.

present participle and gerund of open

Pertaining to the start or beginning of a series of events.

(cricket) describing the first period of play, usually up to the fall of the first wicket; describing a batsman who opens the innings or a bowler who opens the attack