- set something off
- set something off†1. Lit. to ignite something, such as fireworks. •
The boys were setting firecrackers off all afternoon.
•They set off rocket after rocket.
2. Fig. to cause something to begin. •The coach set the race off with a shot from the starting pistol.
•She set off the race with a whistle.
3. Fig. to make something distinct or outstanding. •The lovely stonework sets the fireplace off quite nicely.
•The white hat really sets off Betsy's eyes.
Dictionary of American idioms. 2013.