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velocity

vuh-LOSS-ih-tee /vəˈlɒsɪti/

nounB2GRESATACTTOEFL

technicalacademic

The speed of something in a given direction.

In physics, velocity is a vector quantity (requiring both speed and direction), whereas speed is a scalar quantity (only magnitude).

The story behind the word. From the Latin 'velox', meaning swift or rapid. It entered Middle English through Old French as 'velocite' in the 15th century, initially describing general quickness of movement before Galileo and Newton formalized it in classical mechanics.

Word relationships

speed: Speed is how fast an object is moving regardless of direction, while velocity is speed in a specific direction.

Commonly confused with

acceleration: Velocity is the rate of change of position, while acceleration is the rate of change of velocity.

Word family

velocities (noun): Plural form of velocity.

Collocations

terminal velocity
escape velocity
angular velocity

Example sentences

"To escape Earth's gravity, a spacecraft must reach an escape velocity of approximately 11.2 kilometers per second." Orbital mechanics
"The velocity of money refers to the rate at which money is exchanged from one transaction to another in an economy." Financial metaphor

Memory hook

Think of a 'velociraptor'—a dinosaur famous for its incredible speed and directional agility (velocity). Speed with direction.

When not to use

Do not use 'velocity' as a simple synonym for 'speed' in highly technical contexts unless the direction of travel is specified or implied.

Fun facts

A skydiver falling belly-to-earth reaches a terminal velocity of about 120 mph (190 km/h), where the upward force of drag perfectly balances the downward force of gravity.