What does acceleration mean?
Acceleration is the rate at which velocity changes over time, and it is one of the most fundamental concepts in physics. When a car speeds up, slows down, or rounds a corner, it is accelerating, because its velocity is changing in magnitude or direction. Measured in units such as metres per second squared, acceleration is produced by force, as described by Newton's second law. Beyond physics, the word is widely used figuratively to describe anything that speeds up: an acceleration in economic growth, in the spread of information, or in the pace of daily life. The term carries a sense of momentum and urgency, often implying that change is building rather than merely occurring. Its everyday familiarity makes it a useful bridge between scientific precision and ordinary description, appearing everywhere from engineering reports to news headlines about technological progress.
nounThe rate at which an object's velocity changes with time, or more generally, the process of increasing in speed or happening more quickly.
- In physics: the rate of change of velocity with respect to time.
- The act or process of moving faster or happening more quickly; an increase in speed or pace.
"The sports car's acceleration from zero to sixty was breathtaking."
"The rocket's acceleration pinned the astronauts to their seats."
"There has been a marked acceleration in the pace of technological change over the past decade."
The plural is used mainly in technical contexts when referring to multiple distinct instances or measurements of acceleration, such as different accelerations along different axes.
"The sensors recorded lateral and vertical accelerations during the crash test."
You are accelerating right now — sitting still on Earth, you're being accelerated toward the planet's center at about 9.8 m/s², which is exactly why you feel your weight.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of acceleration
Acceleration derives from the Latin verb 'accelerare', meaning 'to hasten', formed from 'ad-' (toward) and 'celer' (swift). The word entered English in the early 17th century, initially in general senses of hastening before acquiring its precise technical meaning in mechanics. It shares its Latin root with 'celerity', meaning swiftness of movement, and with the modern English verb 'accelerate'.
Related word forms
How acceleration is actually used
Common in both technical/scientific registers and everyday figurative use (e.g. 'the acceleration of history'). In physics it is a vector quantity, so it has both magnitude and direction — an object can accelerate by changing direction even at constant speed.
Easily confused with acceleration
Velocity is speed in a given direction, while acceleration is the rate of change of that velocity over time.
Speed measures how fast something is moving at a moment, whereas acceleration measures how quickly that speed is changing.