【drop off】 —

1. become detached:

• The handle of the door has dropped off.

2. become abruptly much lower:

• The cliff drops off suddenly here, be careful.

3. (coll.) leave a vehicle; get off:

• Thanks for the ride, I’ll 【drop off】 here.

4. become less; deteriorate:

• The quality of performance has dropped off since last year.

5. (coll.) fall asleep:

• I went to bed early but for some reason I couldn’t 【drop off】 .

6. (euph.) die:

• He would probably 【drop off】 quietly with suppressed gout.

【fall off】 —

1. = 【drop off】 1:

• My top button has fallen off.

2. = 【drop off】 2:

• The land falls off here towards the river.

3. = drop off 4:

• Their enthusiasm seems to be falling off a bit.

4. cease participation:

• Some of our most loyal members have now fallen off.