An example of an affair is when a wife cheats on her husband.
An example of an affair is poor spending habits of high level officials.
An example of an affair is a charity dinner.
Their first car was a ramshackle affair.
A difficult affair to manage.
An affair of honor, i. e., a duel.
An affair of love, i. e., an intrigue.
He used a hook-shaped affair with a long handle to unlock the car.
Origin of affair
From American Heritage Dictionary of the English Language, 5th Edition