To explode.
- The bomb went off right after the president left his office.
To fire, especially accidentally.
- The gun went off during their struggle.
To explode metaphorically; to become very angry or overexcited.
- It all went off when the opposing teams' fans met at the railway station.
- When the boss came to know about the scheme, he went off, shouting and throwing everything away.
To begin clanging or making noise.
- The alarm will go off at six a.m.
- Just after he spotted the first plane on the horizon, sirens started to go off around the city.
To stop operating; to switch off.
- We were watching TV when suddenly the power went off.
To depart; to leave.
- Having sated her appetite, she went off in search of a place to sleep.
- I don't know where he's going—he went off without a word.
To putrefy or become inedible, or to become unusable in any way.
- Bugger—the milk's gone off already!
To like gradually less.
- Ever since falling off her bike, she's gone off cycling to work.
- We needed a vet visit because some of the cattle had gone off their feed.
To cure; to set.
- I've got to get the panels aligned quickly now because the epoxy resin will go off within 20 minutes or so.
To pass off; to take place; to be accomplished; to happen.
- The party went off very well.
To ejaculate; to orgasm.
To perform extremely well; to be impressive or attractive; often used to express encouragement.
To follow or extrapolate from something; to judge by.
- Going off the interview alone, she seemed like the perfect employee.
To fall unconscious; to go to sleep; to die.
- One day I'll go off, but until then, I'm in charge around here.
To get married.
- We can only hope she'll go off soon.
To be spent, disbursed or used up.
- All his money goes off as soon as he earns it.
To rant; to talk at length negatively; to insult or criticize.