underground (
http://definr.com/underground)
adj 1: under the level of the ground; "belowground storage areas";
"underground caverns" [syn:
belowground]
2: conducted with or marked by hidden aims or methods;
"clandestine intelligence operations"; "cloak-and-dagger
activities behind enemy lines"; "hole-and-corner
intrigue"; "secret missions"; "a secret agent"; "secret
sales of arms"; "surreptitious mobilization of troops";
"an undercover investigation"; "underground resistance"
[syn:
clandestine,
cloak-and-dagger,
hole-and-corner(a),
hugger-mugger,
hush-hush,
on the quiet(p),
secret,
surreptitious,
undercover]
3: used of independent armed resistance forces; "guerrilla
warfare"; "partisan forces" [syn:
guerrilla(a),
guerilla(a),
irregular]
n 1: a secret group organized to overthrow a government or
occupation force [syn:
resistance]
2: electric underground railway [syn:
metro,
subway,
tube]
adv 1: in or into hiding or secret operation; "the organization was
driven underground"
2: beneath the surface of the earth; "water flowing
underground"