English Dictionary
Definition the Underground in British English
the Underground noun
noun
/ˈʌndə(r)ˌɡraʊnd/
1
a system of public transport consisting of trains that travel in tunnels below a city. The Underground in London is also called the Tube and in some other cities it is also called the Metro. The American word is subway.
Synonyms and related words
2
a group of people who take part in secret and usually illegal activities, especially against a government
