trajectory

American  

[truh-jek-tuh-ree] / trəˈdʒɛk tə ri /

noun

trajectories plural

1. the curve described by a projectile, rocket, or the like in its flight.

2. Geometry. a curve or surface that cuts all the curves or surfaces of a given system at a constant angle.

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trajectory British  

/ -trɪ, trəˈdʒɛktaɪl, trəˈdʒɛktərɪ /

noun

1. the path described by an object moving in air or space under the influence of such forces as thrust, wind resistance, and gravity, esp the curved path of a projectile

2. geometry a curve that cuts a family of curves or surfaces at a constant angle

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trajectory Scientific  

/ trə-jĕk′tə-rē /

1. Physics The line or curve described by an object moving through space.

2. Mathematics A curve or surface that passes through a given set of points or intersects a given series of curves or surfaces at a constant angle.

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Usage

What does trajectory mean? The trajectory of an object is the path it follows once in flight or in motion. The word is especially used in the context of the path of projectiles like rockets, but it can be used in many different contexts. The trajectory of a golf ball is the curved path it follows in the air after being hit by a golf club. The trajectory of an asteroid is the path it follows in space. The potential trajectory of a storm is the route that it may travel. In geometry, trajectory is used in a more specific way to refer to a curve that intersects through a series of points at the same angle. Example: Try to determine the trajectory of the ball as it flies through the air so you can position yourself to catch it.

Other Word Forms

Derived Forms

• trajection
  noun
• trajectile
  adjective

Inflected Forms

Nouns

• trajectories
  plural

Etymology

Origin of trajectory

First recorded in 1660–70; from New Latin trājectōria, noun use of feminine of Medieval Latin trājectōrius “casting over”; equivalent to traject + -tory ¹

Explanation

If you stay on your current trajectory of constant shopping, dining out, and yacht rentals, you'll end up broke. A trajectory is the path of an object through space, or the path of life that a person chooses. Trajectory comes from the Latin trajectoria, which means "throw across." The prefix tra- is short for trans-, which means "across" (think transport and transit) and the ject comes from jacere, which means "throw" and is also the root of the word jet. If you wanted to describe the path of a jet through the sky, you could refer to the jet's trajectory.

Example Sentences

Shares are down 27% in June and, if the downward trajectory holds, are set to notch their worst monthly percentage decline since February 2021, when the stock dropped 32%, according to Dow Jones Market Data.

From Barron's • Jun. 24, 2026

“Short-term we have major drawdowns in inventories, there’s a lot of disruption in the market, and the exact short-term trajectory is difficult to see,” says TradeStation’s David Russell.

From The Wall Street Journal • Jun. 24, 2026

It was a band with changing lineups and a limited discography, but the entire trajectory of the project is well-represented.

From Salon • Jun. 23, 2026

These two wild cards will determine its trajectory.

From MarketWatch • Jun. 23, 2026

It swung from a wire that was sixty-seven meters long; because its trajectory changed over time, he explained, it proved beyond all doubt that the earth rotated.

From "All the Light We Cannot See" by Anthony Doerr

Related Words

• curve
• orbit
• path