on2 S1 W1 [not before noun]
used to say that someone continues to do something or something continues to happen, without stopping:
We decided to play on even though it was snowing.
He went on and on (=talked for a very long time) about his job all evening.
if you move, walk etc on, you move forward or further towards something:
If you walk on a little, you can see the coast.
We drove on towards Manchester.
later than or after a particular time:
Now, forty years on, this is one of the most successful theatres in the country.
From that moment on I never believed a word she said.
if you have something on, you are wearing it:
All he had on was a pair of tattered shorts.
Put your coat on. It's freezing outside.
used to say that something is attached to something else, especially when it is in the correct position [≠ off]:
Is the cover on properly?
Remember to put the lid back on.
used to say that something is written somewhere:
He was wearing a badge with his name on.
in or into a bus, train etc [≠ off]:
The train stopped and two people got on.
if a machine, light etc is on, it is operating [≠ off]:
Who left all the lights on?
The TV's on, but nobody seems to be watching it.
He sat down at the desk and switched on the computer.
if a radio or television programme etc is on, it is being broadcast:
What time is 'Star Trek' on?
if an event is on, it has been arranged and is happening or will happen [≠ off]:
The transport union has confirmed that the strike is definitely on.
I'd avoid the city centre - there's some kind of procession on.
Is the party still on tonight or have they cancelled it?
performing or speaking in public:
You're on in two minutes.
if you are on at a particular time, you are doing your job at that time:
I'm not on again until 2 o'clock tomorrow.
if you have something on, there is something that you must do:
I haven't got anything on tomorrow, so I could see you then.
We've got a lot on at the moment.
14 also off and on
for short periods but not regularly over a long period of time:
He's been smoking for 10 years now, on and off.
to keep complaining to someone or asking someone to do something, especially when this annoys them:
I've been on at him to fix that cupboard for weeks now.
I wish you wouldn't go on at me the whole time!
16 British English informal
to keep talking about something, in a way that is boring or annoying:
He's always going on about money.
I don't know what you're on about!
17 British English spoken
if something is not on, it is not acceptable or reasonable:
I'm sorry, what you're suggesting is just not on!
to be ready or willing to do something that someone has suggested:
Right, how many of you are on for a drink after work?
used tell someone that you accept a bet or an invitation to compete against them:
'I bet you £20 he won't turn up.' 'You're on!'