ngầm in English:

Those stairs will bring you to the underground where the station is.

Tom stood on the platform in Westminster Underground Station.

I hate underground.

Today the underground was closed and the traffic was awful.

Tom slept peacefully as the underground train rattled on its way.

In the underground, to double-cross any member means sure death.

London is such a large city that visitors must use buses and the underground railway to get about.

In the London underground there is a warning to "mind the gap" when boarding the train.

I'd defeated the four sub-bosses and got through the damn long underground labyrinth.

In Britain they call the subway the underground.

When I was in Nurnberg I went by underground.

In London, most people travel by underground, which is called the Tube.

Baker Street underground station is at the junction of Baker Street and Marylebone Road.

I go to work by the underground. Miners work under the ground

If they drive God from the earth, we shall shelter Him underground.

He trusts her implicitly.

That book spoke implicitly to those who run a company.