幽す[yuusu] to confine to a room
幽闇[yuuan] gloom
幽雅[yuuga] refinement
幽界[yuukai] hades
幽閑[yuukan] quiet and secluded

幽鬼[yuuki] ghost
幽客[yuukaku] orchid
幽居[yuukyo] hermitage
幽境[yuukyou] solitude
幽契[yuukei] secret promise made to the gods

共棲[tomoiki] symbiosis
棲家[sumika] dwelling
水棲[suisei] aquatic (life)
棲息[seisoku] inhabiting
同棲[dousei] cohabitation

両棲[ryousei] amphibious
隠棲[insei] secluded life
旧棲[kyuusei] old home
棲み分け[sumiwake] habitat isolation (biology)
両棲動物[ryouseidoubutsu] amphibious animal