Plain English Meaning

Flying in a straight line, at the same height, with the wings flat. The aircraft is not turning, climbing, or descending.

Full Definition

A flightpath in which the aircraft maintains a constant heading and a constant altitude, with the wings level and no climb or descent.

Context Anchor

Seen in instrument flying when using bank control to keep the airplane from drifting into an unwanted turn.

Derivation

Straight comes from an old word meaning stretched out or direct. Level comes from the idea of being even or horizontal. Together, they point to a that does not curve sideways and does not move up or down.