set off

set someone off

to cause someone to become excited and upset. My sister was an unpredictable young woman, and I never knew what would set her off.

See also: set

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set off

to start going somewhere. He got a Guggenheim fellowship and set off for Mexico to write a novel. You need to be fit and well rested before you set off on a hiking trip. When the car broke down, he set out on foot for help.

See also: set

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set off something

1. to cause an explosion. The investigation determined that he probably did not set off the blast deliberately. Apparently the bomb was placed in a locker and someone set it off with a cell phone.

2. to cause something to be noticed or make it more attractive. You look terrific with those black slacks, and the bright blue blouse sets off your eyes.

3. to cause sudden activity. Rumors set off a wave of selling on the stock exchange. If you keep your phone in a pocket and lean up against something, you may accidentally set it off.

See also: set