To turn off is to make a machine or a light stop working. The opposite of turning it on, and just as ordinary.
It splits round an object. There is a driving sense too, since turning off a road means leaving it at a junction, and a turn-off is that junction. And there is an informal noun meaning something that destroys your interest or attraction, so calling something a real turn-off is a personal judgement. Switch off does the same job for machines and is also used about people who stop listening.
1phraseturn offTo make a device or supply stop working.
“Remember to turn off the tap.”
2phraseleaveTo leave a road at a junction.
“You need to turn off just after the bridge.”
Also accepted in games: switch off
Practised in Everyday Verbs, A Man Called Ove
First appears in chapter 2 of A Man Called Ove.
Practise this word