opportunity,suitable/opportune time,right moment,chance,opening,windowoccasion
cause,give rise to,bring about,result in,lead to,prompt,provoke,evoke,elicit,call forth,produce,create,arouse,make (for),generate,engender,originate,effect,bring on,induce,precipitate,stir up,inspire,spark off,trigger,breedoccasion
a particular time or instance of an event.
on one occasion I stayed up until two in the morning
it's the first time that I've had occasion to complain
his death occasioned her much grief