根據中英文雙解字典,"Rifle"==v.t. cut spiral grooves in ( a gun, its barrel or bore). 在(槍, 槍管或槍膛) 中刻出螺旋形凹線;加膛線或來復線於. "Rifle"==Noun.Gun with a long rifled barrel; (pl.) troops armed with rifles;長槍管刻有螺旋形凹線的槍; 來復槍;步槍;(複數)步槍隊. 根據 以上的解釋,本人認為與彈道之意思並不符合,有可能是指飛彈(rocket)的彈道( trajectory==the curve that a body ( as a planet in its orbit) describes in space.) 例如彈道導彈(trajectory ballistic missile), 彈道火箭 (trajectory ballistic rocket). Yip