A hostler or ostler /ˈɒstlər/ is a groom or stableman, who is employed in a stable to take care of horses, usually at an inn. Today the word has acquired additional meanings, particularly in the railroad industry.
The word is spelled "hostler" in American English, but "ostler" in British English. It traces to c.1386, meaning "one who tends to horses at an inn"—and also, occasionally, "innkeeper"—is derived from Anglo-French hostiler (modern French hostelier), itself from Medieval Latin hostilarius "the monk who entertains guests at a monastery", from hospitale "inn" (compare hospital, hospitaller, hospitality). A similar word, hostelero (innkeeper, the one that took care of a hostal), exists in Spanish.
According to the Dictionary of Occupational Titles, a hostler in motor transportation is a type of truck driver who directs trucks or tractors at vehicle parking or docking areas to move, position, or park trucks or trailers.
In the United States railroad industry a hostler is a type of railroad engineer who moves locomotives in and out of service facilities.