[ truh-jek-tuh-ree ]
/ trəˈdʒɛk tə ri /

noun, plural tra·jec·to·ries.

the curve described by a projectile, rocket, or the like in its flight.
Geometry. a curve or surface that cuts all the curves or surfaces of a given system at a constant angle.



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Origin of trajectory

1660–70; <New Latin trājectōria, noun use of feminine of Medieval Latin trājectōrius cast-ing over. See traject, -tory1


tra·jec·tile [truh-jek-til, -tahyl], /trəˈdʒɛk tɪl, -taɪl/, adjectivetra·jec·tion [truh-jek-shuhn], /trəˈdʒɛk ʃən/, noun

Words nearby trajectory Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2020


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.

Where does trajectory come from?

The first records of the word trajectory come from the 1660s. It comes from the Latin trājectōrius, meaning “casting over,” from the verb trāicere, “to cast” or “to throw over or across.” The first part of the word is equivalent to trans-, meaning “across,” and the root jec comes from the Latin verb jacere, meaning “to throw” (the same root forms the basis of motion-related words like projectile, eject, and many others).

Thanks to gravity, what goes up must come down. The path that something follows as it takes the journey up and then down again is its trajectory. When gravity is in play, objects that are thrown or propelled in some way follow a trajectory in the shape of what’s technically known as a parabola, which is basically a kind of curve. The word trajectory is commonly applied to the path of things that travel in this way, but it can be used more generally to simply refer to the route of something from one place to another, such as the trajectory of a storm. It can also be used in a more figurative way, as in career trajectory—meaning the path that one’s career has taken.

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What are some other forms related to trajectory?

  • trajectories (plural)
  • trajectile (adjective)
  • trajection (noun)

What are some synonyms for trajectory?

What are some words that share a root or word element with trajectory?

What are some words that often get used in discussing trajectory?


How is trajectory used in real life?

The word trajectory is commonly used to refer to the path of projectiles like rockets, but it can be used in many different contexts.



Try using trajectory!

Which of the following words is not a synonym of trajectory?

A. path
B. route
C. point
D. track

Example sentences from the Web for trajectory

British Dictionary definitions for trajectory

/ (trəˈdʒɛktərɪ, -trɪ) /

noun plural -ries

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

Derived forms of trajectory

trajectile (trəˈdʒɛktaɪl), adjective
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for trajectory

[ trə-jĕktə-rē ]

Physics The line or curve described by an object moving through space.
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.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.