occasion

An event or happening, or the time of an event or happening.

A significant event, especially a large or important social gathering.

A favorable or appropriate time or juncture: synonym: opportunity.

A cause of or reason for something: synonym: cause.

A need created by a particular circumstance.

Personal requirements or necessities.

To provide occasion for; cause.

(on occasion) From time to time; now and then.

(rise to the occasion) To find the ability to deal with an unexpected challenge.