set off
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.
To balance; make somewhat equal.
Her great wealth, as he thought, set off her plain face.
To begin to go.
They set off for the West in a covered wagon.
We set out for the top of the mountain at dawn. Unfortunately, as we set off, it started to snow heavily, so we decided to head out again later.
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.
To cause to explode.
On July 4 we set off firecrackers in many places.