subterranean

adj. 地下的

substance, substandard, substantial, substantially, substantiate, substantiation, substantive, substantively, substation, substitute, substitute for, substitute...for, substitution, substratum, substructure, subsume, subtenancy, subtenant, subtend, subterfuge, subtitle, subtle, subtlety, subtly, subtopia, subtopic, subtotal, subtract, subtraction, subtropical, suburb, suburban, suburbanite, Suburbia, subvention, subversion, subversive, subversively, subversiveness, subvert,