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

型録[katarogu] catalog
ノイマン型[noimangata] Neumann-type (computer)
凹型[ougata] concavity
関数原型[kansuugenkei] function prototype
畸型[kikei] birth defect

金型[kanagata] metal pattern
靴型[kutsugata] shoe last
型紙[katagami] pattern paper (for dressmaking)
型染め[katazome] stencil dyeing

アルファ線[arufasen] alpha rays
エックス線[ekkususen] X-ray
サイン曲線[sainkyokusen] sinusoid
スピード線[supiidosen] speed lines
緯線[isen] parallel

一次線輪[ichijisenrin] primary coil
一線[issen] line
一直線[icchokusen] straight line
一番線[ichibansen] track no. 1
一塁線[ichiruisen] first-base line