Cambridge Dictionaries online Cambridge Dictionaries online

The most popular online dictionary and thesaurus for learners of English

English definition of “underground”

underground

adjective, adverb (SECRET)    /ˌʌn.dəˈɡraʊnd/ US  /-dɚ-/
describes an activity that is secret and usually illegal: an underground newspaper/movement The Communist Party was forced (to go) underground, and its leaders went into hiding.Secrecy and privacyLegal and illegal
(Definition of underground adjectiveadverb (SECRET) from the Cambridge Advanced Learner's Dictionary & Thesaurus © Cambridge University Press)
Focus on the pronunciation of underground

Browse related topics

You are looking at an entry to do with Legal & illegal, but you might be interested in these topics from the Law and the police topic area:

Definitions of “underground” in other dictionaries

Word of the Day

well in (with)

to have a good relationship with someone in which they like you and from which you get an advantage

Word of the Day

Blog

Read our blog about how the English language behaves.

Learn More

New Words

Find words and meanings that have just started to be used in English, and let us know what you think of them.

Learn More