Definition
A wind blowing in the same direction as the aircraft's flight path, pushing it forward and increasing groundspeed relative to airspeed.
Plain English
Wind coming from behind the aircraft, helping it move faster across the ground.
Context Anchor
You will see tailwind used in weather reports, runway selection, takeoff and landing planning, and flight time calculations.
Derivation
From 'tail' (the rear of the aircraft) plus 'wind.' The name describes where the wind is coming from -- behind the tail -- which is why it pushes the aircraft along.
Why Pilots Care
Tailwinds increase groundspeed but decrease airspeed over the wing, requiring longer takeoff and landing distances and reducing climb performance.
Intuition Check
Do not assume a tailwind is always helpful. It can help you cover ground faster in cruise, but it can make takeoffs and landings require more runway.
Example Sentence 1
With a 30-knot tailwind at altitude, we arrived twenty minutes ahead of schedule.
Example Sentence 2
During the approach briefing the crew confirmed the tailwind component stayed within landing limits.