v. 1. To decorate through contrast; balance by difference. The bright colors of the birds were set off by the white snow. A small gold pin set off her plain dark dress. 2. To balance; make somewhat equal. Her great wealth, as he thought, set off her plain face. 3a. To begin to go. They set off for the West in a covered wagon.
Compare: SET OUT. 3b. To cause to begin. A letter from home set off an attack of homesickness. An atomic explosion is created by setting off a chain reaction in the atom.
Compare: TOUCH OFF. 3c. To cause to explode. On July 4 we set off firecrackers in many places.