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

垂迹[suijaku] temporary manifestation by a buddha (in order to save people)
筆迹[hisseki] handwriting
真迹[shinseki] true autograph

事迹[jiseki] evidence
本地垂迹説[honjisuijakusetsu] manifestation theory (holding that Shinto gods are manifestations of buddhas)
迹門[shakumon] first half of the Lotus Sutra, in which the Buddha appears as a spatiotemporally restricted being