The Collaborative International Dictionary
Broad gauge \Broad" gauge`\ (Railroad) A wider distance between the rails than the ``standard'' gauge of four feet eight inches and a half. See Gauge.
Wiktionary
alt. (cx rail transport English) A railway gauge (distance between the two lines) that is greater than the standard gauge (often quoted as 56 inches) n. (cx rail transport English) A railway gauge (distance between the two lines) that is greater than the standard gauge (often quoted as 56 inches)
WordNet
n. a railroad track (or its width) broader than the standard 56.5 inches
Wikipedia
Broad gauge railways use a track gauge (distance between the rails) greater than the standard gauge of .
Usage examples of "broad gauge".
The railroads in Russia are broad gauge, the rails set much wider apart, so the trains are built quite different.
Rolling stock on the rail-ways had first to be converted from the Russian broad gauge to the narrow European gauge.
It's Santander made, anyway-standard 4-4-2, rebuilt for the Imperial broad gauge.
So most of the Southern railroads had standardized their tracks to the same broad gauge, and Henry had managed to get Longarm by rail to the head of navigation on the Rio Grande.