drop off phrasal verb ( see also ↑ drop )
1 . to begin to sleep:
She kept dropping off at her desk.
I must have dropped off to sleep.
2 . drop somebody/something ↔ off to take someone or something to a place by car and leave them there on your way to another place:
I’ll drop you off on my way home.
3 . to fall to a lower level or amount:
The number of graduates going into teaching has dropped off sharply.