You can refer to an important or interesting event or situation as `the affair'. the damage caused to the CIA and FBI in the aftermath of the Watergate affair
If an event or a series of events has been mentioned and you want to talk about it again, you can refer to it as the affair. The government has mishandled the whole affair The affair began when customs officials inspected a convoy of 60 tankers = business, matter
That which is done or is to be done; matter; concern; as, a difficult affair to manage; business of any kind, commercial, professional, or public; often in the plural
You can describe the main quality of an event by saying that it is a particular kind of affair. Michael said that his planned 10-day visit would be a purely private affair
You can describe an object as a particular kind of affair when you want to draw attention to a particular feature, or indicate that it is unusual. All their beds were distinctive; Mac's was an iron affair with brass knobs
a vaguely specified social event; "the party was quite an affair"; "an occasion arranged to honor the president"; "a seemingly endless round of social functions"