Source : Webster's Revised Unabridged Dictionary (1913)

Trajectory \Tra*ject"o*ry\, n.; pl. {Trajectories}. [Cf. F.
   trajectoire.]
   The curve which a body describes in space, as a planet or
   comet in its orbit, or stone thrown upward obliquely in the
   air.

Source : WordNet®

trajectory
     n : the path followed by an object moving through space [syn: {flight}]