空洞[kuudou] cave
空洞化[kuudouka] making hollow
鐘乳洞[shounyuudou] limestone cave (cavern, grotto)
洞窟[doukutsu] cave
洞穴[douketsu] cave

洞察[dousatsu] discernment
風洞[fuudou] wind tunnel
空洞化現象[kuudoukagenshou] (economic) hollowing-out phenomenon
洞見[douken] insight

虚虚実実[kyokyojitsujitsu] full of wiles and tricks
虚しく[munashiku] in vain
虚栄[kyoei] vanity
虚偽[kyogi] untrue
虚空[kokuu] empty space

虚空蔵[kokuuzou] Akasagarbha (bodhisattva)
虚言[kyogen] falsehood
虚構[kyokou] fiction
虚弱[kyojaku] feebleness
虚飾[kyoshoku] ostentation

だぼ鯊[dabohaze] goby (fish)
真鯊[mahaze] yellowfin goby (Acanthogobius flavimanus)
顎鯊[agohaze] forktongue goby (Chaenogobius annularis)
糸引鯊[itohikihaze] Myersina filifer (species of goby)

洞鯊[urohaze] Glossogobius olivaceus (species of goby)
極楽鯊[gokurakuhaze] barcheek goby (Rhinogobius giurinus)
跳鯊[tobihaze] mudskipper (Periophthalmus cantonensis)
蚯蚓鯊[mimizuhaze] flat-headed goby (Luciogobius guttatus)