Plain English Meaning

Putting the wrong kind of fuel in the airplane. Piston engines need avgas; turbine engines need jet fuel. Mixing them up is misfueling.

Full Definition

The act of servicing an aircraft with the wrong type of fuel for its engine — most commonly putting jet fuel (kerosene-based, such as Jet A) into a piston-engine aircraft designed for aviation gasoline (avgas), or the reverse.

Context Anchor

Encountered during fueling, preflight inspection, fuel-sample checks, and review of fuel receipts or fuel placards near the filler caps.

Derivation

Built from the prefix 'mis-' (wrongly, badly) and 'fueling.' The prefix flags an error in the action — not just fueling, but fueling done incorrectly.