Plain English Meaning

A line of red lights set into the taxiway surface that means stop. When ATC clears you to continue, they turn the lights off, and only then may you cross.

Full Definition

A row of steady, in-pavement red lights installed across a taxiway at a runway holding position, used during low-visibility operations to indicate that an aircraft or vehicle must stop and may not cross until the lights are extinguished by ATC.

Context Anchor

Seen while taxiing at larger airports, especially during low-visibility operations under a Surface Movement Guidance Control System.

Derivation

“Stop” means to halt, and “bar” here means a line or barrier across a path. The term helps because the lights form a lighted barrier across the taxiway: they are not just marking the pavement; they are telling you to stop.