# Word choice in this sentence: trajectory vs. vector

I'm editing a short piece of fiction where the author has left brackets around specific items that they want looked at, and this one has me a little bit stumped.

In the scene, a character has jumped out of an airborne vehicle and is wearing a jet pack that will allow her to travel additional distance and, obviously, not crash into the ground. This jet pack has been malfunctioning, so she has been falling straight downward, but then it suddenly kicks into gear. Here's the sentence:

The repulsion system kicked in and she shot forward, flinching as she came within meters of clipping the edge of a building. She was still traveling faster than she should have been, but at least now the majority of that speed was on a horizontal trajectory [vector?].

There are those brackets included around "vector" and I'm not sure whether it or "trajectory" would be the best word choice, since it's addressing the forward momentum more than it's actually addressing the character.

Trajectory definition:

The path followed by a projectile flying or an object moving under the action of given forces.

Vector definition:

A quantity having direction as well as magnitude, especially as determining the position of one point in space relative to another.

I probably wouldn't have thought twice about the word "trajectory" if those brackets hadn't been included, but now I'm second-guessing (and I assume the writer was, too). Since this character has both speed and direction, would "vector" be the best word choice, or should I just leave it as "trajectory" since it's also sort of talking about the path she's following? Which word would most accurately fit here?

## 2 Answers

Definitely not “vector”. Mathematical and not in common use. Sounds weird.

“Trajectory” is a bit technical but seems fine in the context.

If you prefer plain English you could always use “direction”.

• Cool, that's kind of what I was thinking. And while trajectory is a little bit technical, based on what I know about the character and her professional background, it does seem like a word she would use. Thanks for the input!
– EJF
May 31, 2016 at 19:27

I agree with @David. The use of vector in here would render the setence a tad bit weird..

I'd go with "trajectory" as well. It sounds technical but maybe that is what he was aiming for; otherwise, the author would have chosen a simpler, more commonplace word.