- a narrow walkway, especially one high above the surrounding area, used to provide access or allow workers to stand or move, as over the stage in a theater, outside the roadway of a bridge, along the top of a railroad car, etc.
- a narrow ramp extending from the stage into the audience in a theatre, nightclub, etc, esp as used by models in a fashion show
- a narrow pathway over the stage of a theatre, along a bridge, etc
1885, “long, narrow footway,” from cat (n.) + walk (n.); in reference to such narrowness of passage one has to cross carefully, as a cat walks. Originally of ships and theatrical back-stages. Application to fashion show runways is by 1942.