on

In the state of being active, functioning or operating.

All the lights are on, so they must be home.

Happening; taking place; being or due to be put into action.

We had to ration our food because there was a war on.

Some of the cast went down with flu, but the show's still on.

Happening; taking place; being or due to be put into action.

"Five bucks says the Cavs win tonight." ―"You're on!"

If he wants a fight, he's on!

Fitted; covering or being worn.

Your feet will soon warm up once your socks are on.

I was trying to drink out of the bottle while the top was still on!

Of a stated part of something, oriented towards the viewer or other specified direction.

The photograph shows the UFO side on.

edge on, side on, end on, face on

To an operating state.

turn the television on

So as to cover or be fitted.

The lid wasn't screwed on properly.

Put on your hat and gloves.

Along, forwards (continuing an action), onwards.

The policeman moved the tramp on.

Drive on past the railway station.

In continuation, at length.

and so on

He rambled on and on.

Later.

Ten years on, nothing had changed in the village.

Indicating position or location.

A vase of flowers stood on the table.

Please lie down on the couch.

Indicating position or location.

He had a scar on the side of his face.

There is a dirty smudge on this window.

Indicating position or location.

He wore old shoes on his feet.

Indicating position or location.

The lighthouse that you can see is on the mainland.

The suspect is thought to still be on the campus.

Indicating position or location.

We live on the edge of the city.

on the left, on the right, on the side, on the bottom