御古[ofuru] used article (esp. clothes)
手古摺る[tekozuru] to have much trouble
土耳古[toruko] Turkey
下稽古[shitageiko] rehearsal
懐古[kaiko] recalling the old days

擬古[giko] imitation of classical styles
擬古文[gikobun] classical style
稽古[keiko] practice
遠古登点[wokototen] marks to aid in reading Chinese classics
古え[inishie] antiquity

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