Definition
To rotate the blades of a variable-pitch propeller so their leading edges point directly into the oncoming airflow, presenting the thinnest possible profile to the relative wind. A feathered propeller produces minimal drag and stops rotating, and is used after an engine failure on multi-engine airplanes or to shut down an engine in flight on turboprops.
Plain English
To turn the propeller blades edge-on to the wind so they stop spinning and create as little drag as possible. Pilots feather a propeller when the engine has failed or been shut down, so the dead engine doesn't slow the airplane down.
Context Anchor
Used with feathering propeller systems, especially on airplanes where a stopped or failed engine could leave a propeller creating heavy drag.
Derivation
From the everyday sense of "feathering an oar" — turning the oar blade flat to slice cleanly through the air on the return stroke instead of catching the wind. The propeller blade is turned the same way: edge-first into the airflow so it stops resisting it.
Why Pilots Care
Feathering a failed engine’s propeller removes most of the asymmetric drag that would otherwise yaw the aircraft and degrade climb performance on the remaining engine.
Analogy
It is like turning a flat board edge-first into a strong wind. The wind has much less surface to push against, so the board is easier to hold.
Intuition Check
Feather does not mean making something soft or light here. It means turning the propeller blades edge-on to the airflow to reduce drag.
Example Sentence 1
After the right engine failed, the pilot identified the dead engine and feathered the propeller to reduce drag.
Example Sentence 2
The checklist called for feathering the propeller on the inoperative engine before attempting a single-engine climb.