subagency subatomic subcellular subclass subcommittee subcompact subconscious subculture subdivision subdomain subdue subdued subglacial subgraph subgroup subhead subject sublease sublet sublime submachine submarine submenu submerge submersible submission submit subnational subnet suboptimal suborbital subpage subprime subroutine subscale subscribe subscription subsection subsector subsequent subset subsidiary subsidy subsistence subsonic subspecies substandard substation substitute subsurface subsystem subterranean subtext subtitle subtract subtropical subtype suburb suburban subway subwoofer