Synonyms and related words :
aa, abyssal rock, basalt, base, basement, basic, basis, bearing wall, bed, bedding, belly, block lava, bottom, bottom side, bottommost, brash, breccia, breech, buttocks, central, conglomerate, crag, deepest, downside, druid stone, essential, festooned pahoehoe, floor, flooring, focal, fond, footing, foundation, fundament, fundamental, gneiss, granite, ground, grounds, groundwork, hardpan, igneous rock, indispensable, infrastructure, lava, life-and-death, life-or-death, limestone, living rock, lower side, lower strata, lowest, lowest layer, lowest level, lowest point, magma, mantlerock, material, metamorphic rock, monolith, nadir, nether side, nethermost, nethermost level, of vital importance, pahoehoe, pavement, pillar, pillow lava, porphyry, principle, pudding stone, radical, regolith, riprap, rock, rock bottom, rock-bottom, root, ropy lava, rubble, rubblestone, rudiment, sandstone, sarsen, schist, scoria, scree, seat, sedimentary rock, shelly pahoehoe, sill, solid ground, solid rock, stereobate, stone, stylobate, substantive, substratum, substruction, substructure, talus, terra firma, tower, tufa, tuff, underbelly, underbuilding, undercarriage, undergirding, underlayer, underlying level, undermost, underneath, underpinning, underside, understruction, understructure, vital