暗い[kurai] dark
暗がり[kuragari] darkness
暗に[anni] implicitly
暗やみ[kurayami] darkness
暗うつ[anutsu] gloom

暗雲[anun] dark clouds
暗褐色[ankasshoku] dark brown
暗きょ[ankyo] subterranean drain
暗君[ankun] foolish ruler
暗号[angou] code

暗渠[ankyo] subterranean drain
渠魁[kyokai] ringleader
溝渠[koukyo] ditch
出渠[shukkyo] leaving the (repair) dock
入渠[nyuukyo] entering a dock

函渠[kankyo] drain with an oblong cross-section
乾船渠[kansenkyo] dry dock
船渠[senkyo] dock
暗渠排水[ankyohaisui] underdrainage
合流渠[gouryuukyo] combined sewer