trajectory       
noun [ C ]  physics, military specialized uk/trəˈdʒek.tər.i/ us/trəˈdʒek.tɚ.i/
 (射体在空中的)轨道,轨迹
the curved path that an object follows after it has been thrown or shot into the air
  the trajectory of a bullet/missile 子弹/导弹的弹道 
 Idiom   
be on an upward/downward trajectoryidiom  在上升/下降
to be getting higher or lower
  The government is now claiming that inflation is on a downward trajectory. 政府现在宣称通货膨胀呈现下降趋势。