Definition
To increase the velocity of a body, or to change its velocity by altering speed, direction, or both. In aviation, an aircraft accelerates whenever a net force acts on it, producing a change in its motion.
Plain English
To speed up, or more broadly, to change how fast or in what direction something is moving.
Context Anchor
Seen in discussions of thrust, takeoff roll, climb, go-arounds, and any situation where adding power causes the aircraft to gain speed.
Derivation
From the Latin 'accelerare,' meaning 'to hasten' or 'to quicken' (from 'ad-' meaning 'to' and 'celer' meaning 'swift'). In physics and aviation, the meaning is broader than just 'speeding up' -- it includes any change in motion.
Why Pilots Care
Safe takeoff and climb require controlled acceleration to reach flying speed without exceeding runway length.
Grounding Statement
If the airplane is being pushed forward more strongly than it is being held back, it will accelerate.
Intuition Check
Do not read accelerate as simply “go fast.” An aircraft can be fast and not accelerating; accelerate means its speed or direction of motion is changing.
Example Sentence 1
On the takeoff roll, the aircraft accelerates until it reaches rotation speed.
Example Sentence 2
After liftoff the airplane continued to accelerate while climbing through 500 feet.