Go off has a few meanings. It can mean to leave a place. They had to go off for dinner. It can mean to suddenly start making noise. Did you hear the alarm go off this morning? It can be used when a ...

Phrasal verbs, or multi-word verbs, are verbs that are combined with one or two particles (a preposition or adverb), for example, 'up' or 'down', to make verbs with new meanings.