subterranean

Definition of Subterranean in English :

1. subterranean, subterraneous

being or operating under the surface of the earth

Example Sentences:
'subterranean passages'
'a subsurface flow of water'

2. subterranean, subterraneous, ulterior

lying beyond what is openly revealed or avowed (especially being kept in the background or deliberately concealed)

Example Sentences:
'subterranean motives for murder'
'looked too closely for an ulterior purpose in all knowledge'

WordNet Lexical Database for English. Princeton University. 2010.

Subterranean

adjective

1. Also: subterraneous, subterrestrial

situated, living, or operating below the surface of the earth

2.

existing or operating in concealment

adjective

1.

lying beneath the earth's surface; underground

2.

secret; hidden

: Also ˌsubterˈraneous

noun

3.

one who lives underground

adj.

1. Situated or operating beneath the earth's surface; underground.

2. Hidden; secret: subterranean motives for murder.