双節棍[nunchaku] nunchaku (two linked fighting sticks)
一双[issou] pair (esp. of folding screens)
一卵性双生児[ichiranseisouseiji] identical twins
双紙[soushi] written work (esp. a bound text, as opposed to a scroll)
自己双対[jikosoutsui] self dual

双刃[moroha] double-edged
双暗車[souansha] twin propellers
双殻類[soukakurui] bivalves
双眼[sougan] both eyes

前翅[zenshi] fore-wing (of insect)
鳳翅鐘[houshitou] wing-rings (weapon)
双翅類[soushirui] dipterans
翅斑蚊[hamadaraka] anopheles mosquito (any mosquito of genus Anopheles, capable of carrying malaria)
半翅目[hanshimoku] Hemiptera

隠翅虫[hanekakushi] rove beetle
翅脈[shimyaku] wing veins (of an insect)
後翅[koushi] hindwing
鞘翅類[shoushirui] coleopterans

異類[irui] varieties
一類[ichirui] same kind
円虫類[enchuurui] round worms
塩類[enrui] salts
塩類溶液[enruiyoueki] saline

貝類[kairui] shellfish
柑橘類[kankitsurui] citrus fruits
希土類[kidorui] rare earth
魚貝類[gyokairui] marine products
魚類[gyorui] fish