subterraneous

CIDE DICTIONARY

subterraneous, 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.  [1913 Webster]

ROGET THESAURUS

subterraneous

Depth

N depth, deepness, profundity, depression, hollow, pit, shaft, well, crater, gulf, bowels of the earth, botttomless pit, hell, soundings, depth of water, water, draught, submersion, plummet, sound, probe, sounding rod, sounding line, lead, bathymetry, sonar, side-looking sonar, bathometer, deep, deep seated, profound, sunk, buried, submerged, subaqueous, submarine, subterranean, subterraneous, subterrene, underground, bottomless, soundless, fathomless, unfathomed, unfathomable, abysmal, deep as a well, bathycolpian, benthal, benthopelagic, downreaching, yawning, knee deep, ankle deep, beyond one's depth, out of one's depth, over head and ears, mark twine, mark twain.