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velocity

vuh-LOSS-ih-tee /vəˈlɒsəti/

nounB2SATACTTOEFLIELTS

GeneralTechnicalAcademic

The speed of something in a given direction.

In physics and engineering, velocity is a vector quantity, meaning it has both a magnitude (speed) and a specific direction. Speed is just '60 mph', while velocity is '60 mph due North'.

The story behind the word. Velocity comes from the Latin 'velox', meaning 'swift' or 'fast'. It entered Middle English through Old French as 'velocite' to describe rapid motion, but it was Galileo and Isaac Newton who formalized it into a precise mathematical term representing the rate of change of position over time in a specific direction.

Word relationships

speed: Speed is a scalar quantity (only magnitude), while velocity is a vector quantity (magnitude and direction).

stationariness: The state of being completely still or having zero velocity.

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, referring to multiple speed-direction vectors.

Collocations

terminal velocity
angular velocity
high velocity
escape velocity

Example sentences

"The rocket reached escape velocity and successfully broke free from the Earth's gravitational pull." An aerospace launch report
"The water flows through the narrow nozzle at a high velocity, creating enough force to cut through steel." A fluid dynamics simulation

Memory hook

Think of a 'velociraptor'—a dinosaur famous for its incredible 'velocity' (speed and agile direction changes) when hunting. Velocity is speed with a steering wheel.

When not to use

Do not use velocity when direction is completely irrelevant or unknown; in casual conversation, 'speed' is usually more natural.

Fun facts

The terminal velocity of a falling skydiver in a standard belly-to-earth position is about 120 mph (190 km/h), but they can increase this velocity by diving headfirst.
Light travels at a constant velocity of approximately 299,792 kilometers per second in a vacuum.