set off

(idiomatic, intransitive) To leave; to begin a journey or trip.

(idiomatic, transitive) To begin; to cause; to initiate.

(idiomatic, transitive) To cause to explode, let off.

(idiomatic, transitive) To put into an angry mood; to start (a person) ranting or sulking, etc.

(idiomatic, transitive) To enhance by emphasizing differences.

(idiomatic, transitive) To offset, to compensate for: to reduce the effect of, by having a contrary effect.

(printing, historical) 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.