pony express pony engine • pony grass · · · Info · Definitions · Characters · · pony express · · Text Common · · Latin · · Scripts 12 · · Length 4 · · Syllables Definitions · · · (noun) express mail carried by relays of riders on horseback; especially between Missouri and California around 1860. Synonyms: pony express. · · Noun Definition 1 Characters · · space U+0020 e latin small letter e U+0065 n latin small letter n U+006E o latin small letter o U+006F p latin small letter p U+0070 r latin small letter r U+0072 s latin small letter s U+0073 x latin small letter x U+0078 y latin small letter y U+0079