fall off phrasal verb ( see also ↑ fall )
1 . fall off (something) if part of something falls off, it becomes separated from the main part:
The door handle keeps falling off.
A button had fallen off her jacket.
2 . if the amount, rate, or quality of something falls off, it decreases SYN fall OPP rise :
Audience figures fell off during the second series of the programme.
3 . somebody nearly/almost fell off their chair spoken used to say that someone was very surprised when something happened:
When I saw my brother on the stage I nearly fell off my chair.
⇨ fall off the back of a lorry at ↑ lorry