What do you think set off means? To turn off something? To end something? Well, what it really means is to leave. It’s usually used when you talk about traveling.
Here’s an example:
- “We’d better set off early tomorrow. We have a long journey.”
- “We’d better leave early tomorrow. We have a long journey.”
- “Richard will set off at nine o’clock. That means he will be here at 10.30″
Hope it helps!