Definition
The speed at which an aircraft moves on the ground under its own power, kept slow enough that the airplane can be stopped promptly with normal braking and steered safely in the existing surface, traffic, and visibility conditions. A common rule of thumb is a speed equivalent to a brisk walk in congested areas (ramps, parking, near other aircraft) and slightly faster on open taxiways, never so fast that stopping or turning becomes uncertain.
Plain English
How fast you move the airplane while driving it on the ground. The right speed is one you can stop and steer at safely, given what's around you.
Context Anchor
Encountered during ground operations, especially when moving from parking to the runway or from the runway back to parking.
Derivation
From the verb 'taxi,' which originally referred to a taxicab. Early aviators borrowed the word because an airplane moving slowly on the ground -- not yet flying -- looked and behaved like a cab driving along. 'Taxiing speed' simply means the speed used during that ground-driving phase.
Why Pilots Care
Excessive taxiing speed reduces the pilot's ability to stop or turn in time, raising the risk of collisions with other aircraft, vehicles, or obstacles.
Grounding Statement
A good taxiing speed lets the pilot stop smoothly and quickly if something appears ahead.
Intuition Check
Taxiing speed does not mean the same speed everywhere on the airport. It means a safe ground speed for the situation, slow enough to stay in control and stop if needed.
Example Sentence 1
He reduced taxiing speed to a walking pace as he approached the crowded ramp.
Example Sentence 2
Maintaining proper taxiing speed on wet pavement kept the aircraft from building momentum that could make stopping difficult.