ローム層[roomusou] stratum of loam
亜成層圏[aseisouken] substratosphere
一層[issou] much more
沖積層[chuusekisou] alluvium
下層[kasou] lower strata (classes)

下層階級[kasoukaikyuu] proletariat
下層社会[kasoushakai] the underworld
下層土[kasoudo] subsoil
化石層[kasekisou] fossil bed
階層[kaisou] class

意味深重[imishinchou] with profound (often hidden) meaning
奥深い[okufukai] profound
海深[kaishin] depth of the sea
疑い深い[utagaibukai] doubting
興味深い[kyoumibukai] very interesting

深ける[fukeru] to get late
根深い[nebukai] deep-rooted
思慮深い[shiryobukai] prudent
執念深い[shuunenbukai] vindictive
嫉妬深い[shittobukai] (deeply) jealous