(adj) lying beyond what is openly revealed or avowed (especially being kept in the background or deliberately concealed); ; - Bertrand Russell, Syn. subterraneous, ulterior, Example:subterranean motives for murder; looked too closely for an ulterior purpose in all knowledge
The Collaborative International Dictionary of English (GCIDE) v.0.53 Collaborative International Dictionary (GCIDE)
{ } a. [ L. subterraneus; sub under + terra earth. See Terrace. ] Being or lying under the surface of the earth; situated within the earth, or under ground; as, subterranean springs; a subterraneous passage. -- Sub`ter*ra"ne*ous*ly, adv. [1913 Webster]