Plain English Meaning

The nose drops on its own, without the pilot pushing it down. It happens because the wing has stopped producing enough lift to hold the airplane's nose up.

Full Definition

A sudden drop of the airplane's nose that occurs without the pilot moving the controls to cause it. In stall training, it is the natural result of the wing exceeding its critical angle of attack: lift collapses, the nose falls, and angle of attack reduces, allowing the wing to begin flying again.

Context Anchor

Seen in stall recognition and recovery discussions, especially when describing what the airplane may do as a stall develops or breaks.

Derivation

"Uncommanded" simply means the pilot did not command (order) it to happen through the controls. The phrase is used to distinguish a pitch change caused by aerodynamics from one caused by input.