1.
see drop 9
2.
If you drop off to sleep, you go to sleep. ( INFORMAL )
I must have dropped off to sleep...
Just as I was dropping off, a strange thought crossed my mind.
PHRASAL VERB : V P to sleep , V P
3.
If the level of something drops off , it becomes less.
Sales to the British forces are expected to drop off...
= fall
PHRASAL VERB : V P