The word underground is a noun. Underground means (1) electric underground railway, (2) a secret group organized to overthrow a government or occupation force.
Underground is also an adjective that means (1) used of independent armed resistance forces, (2) under the level of the ground.
Underground is also an adverb that means (1) beneath the surface of the earth, (2) in or into hiding or secret operation.
The following articles and web pages elaborate on the word underground.
This website contains an enormous amount of information about weather around the world. Besides up to date forecasts, there are photos and trip planners. Users can select time zones, language, and metric or English units. There are also maps and storm warnings. Users can register and keep a list of cities for which they want to keep track of the weather.
Iran's Revolutionary Guards said they launched ballistic missiles from "the depths of the Earth" on Wednesday during the last day of military exercises near sensitive Gulf waters. ...
Yahoo. Wednesday, 29 Jul 2020 11:19:00 -0400.
The following digital image illustrates the word underground.