(bound form) refers to vehicles having the same axle width or railroads having the same track gauge; often refers to standardizing measurements and systems

(literary) unified or standardized; having one law or culture throughout the country; often used in the phrase 书同文 shū​tóng​wén, 车同轨 chē​tóng​guǐ meaning standardized writing and standard axle widths

(literary) using the same methods, rules, or standards; following the same path or principle

(literary) to travel along the same road or in the same carriage

(literary) vassal states or domains that share the same system of rites and music