'drop off' definitions:

Definition of 'drop off'

From: WordNet
verb
Fall or diminish; "The number of students in this course dropped off after the first test"
verb
Change from a waking to a sleeping state; "he always falls asleep during lectures" [syn: fall asleep, dope off, flake out, drift off, nod off, drop off, doze off, drowse off] [ant: arouse, awake, awaken, come alive, wake, wake up, waken]
verb
Leave or unload; "unload the cargo"; "drop off the passengers at the hotel" [syn: drop, drop off, set down, put down, unload, discharge]
verb
Retreat [syn: fall back, lose, drop off, fall behind, recede] [ant: advance, gain, gain ground, get ahead, make headway, pull ahead, win]
verb
Get worse; "My grades are slipping" [syn: slip, drop off, drop away, fall away]