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

陰極[inkyoku] cathode
陰極線[inkyokusen] cathode rays
陰極線管[inkyokusenkan] cathode-ray tube
危極[kikyoku] crisis
窮極[kyuukyoku] ultimate

究極目的[kyuukyokumokuteki] extreme purpose
極く[goku] quite
極み[kiwami] height
極めて[kiwamete] exceedingly
極悪[gokuaku] heinous