2un·der·ground 
/ˌʌndɚˈgraʊnd/ adverb
/ˌʌndɚˈgraʊnd/ adverb 1 : below the surface of the earth
▪ The wires run underground. ▪ animals that live underground 2 : in or into a place that is hidden or secret : out of the view of the public
▪ They had been living underground as fugitives. ▪ The political party went underground [=started working in secret] after the new government took power.
▪ The wires run underground. ▪ animals that live underground
▪ They had been living underground as fugitives. ▪ The political party went underground [=started working in secret] after the new government took power.
