Plain English Meaning
The airplane is flying with its wings flat across the horizon, not tilted to either side, so it is going straight rather than turning.
Full Definition
A flight attitude in which the airplane's lateral axis is parallel to the horizon, with no bank angle to either the left or right. In this attitude, lift acts vertically and the airplane neither turns nor rolls.
Context Anchor
Seen in maneuver descriptions such as S-turns, where the pilot rolls out of a turn and briefly returns the airplane to an unbanked attitude.
Why Pilots Care
Wings level establishes a stable reference for timing reversals and prevents unintended or during precision .