- a width of 56.5 in (143.5 cm) between the rails of a railroad track, established as standard
- a railroad having such a gauge
- a locomotive or car for tracks of such a gauge
See standard gauge in American Heritage Dictionary 4
- A railroad track having a width of 56 1/2 inches (143.5 centimeters).
- A railroad or railroad car built to standard gauge specification.
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