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

ロケット発射筒[rokettohasshatou] rocket launcher
依託射撃[itakushageki] firing from elbow rests
威嚇射撃[ikakushageki] warning shot
一斉射撃[isseishageki] volley firing
火焔放射器[kaenhoushaki] flamethrower

間接照準射撃[kansetsushoujunshageki] indirect fire
騎射[kisha] shooting on horseback
逆噴射[gyakufunsha] reverse thrust
曲射[kyokusha] high-angle fire
曲射砲[kyokushahou] howitzer