hostler
noun
hos·tler ˈhä-slər 
ˈä-
variants or less commonly ostler
ˈä-slər
1
: one who takes care of horses or mules
2
: one who moves locomotives in and out of a roundhouse
also : one who services locomotives
Example Sentences
Recent Examples on the Web More than halfway through the film, Manny and Buck discover a formerly napping hostler, Sara. 
David Reamer, Anchorage Daily News, 12 Apr. 2021 Harris, who had worked as a hostler for the county sheriff, was arrested a short time later and taken to the jail on Main Street in Bel Air. David Anderson, The Aegis, 16 May 2017
David Reamer, Anchorage Daily News, 12 Apr. 2021 Harris, who had worked as a hostler for the county sheriff, was arrested a short time later and taken to the jail on Main Street in Bel Air. David Anderson, The Aegis, 16 May 2017 Word History
Etymology
Middle English hostiller, osteler "innkeeper, servant at an inn attending horses, person keeping horses for hire" — more at hosteler
First Known Use
14th century, in the meaning defined at sense 1