To leave; to begin a journey or trip.
He set off in search of better opportunities.
To begin; to cause; to initiate.
I had no idea that one simple comment would set off such a huge argument.
To cause to explode, let off.
What a tragedy, that someone would set off a bomb in a crowded place.
To make angry.
Don't set him off or he won't shut up all day.
To enhance by emphasizing differences.
Her plain white dress was set off by a bright red stole.
To offset, to compensate for: to reduce the effect of, by having a contrary effect.
My taxes did not increase because the amount of my raise was set off by my losses in the stock market.
To deface or soil the next sheet; said of the ink on a freshly printed sheet, when another sheet comes in contact with it before it has had time to dry.