1.
see drop 9
2.
If you ~ 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 ~...
= fall
PHRASAL VERB: V P