[ noun ] someone employed in a stable to take care of the horses <noun.person>
Hostler \Hos"tler\, n. [OE. hosteler, osteler, innkeeper, OF. hostelier, F. h[^o]telier. See {Hostel}, and cf. {Hospitaler}, {Hosteler}.] 1. An innkeeper. [Obs.] See {Hosteler}.
2. The person who has the care of horses at an inn or stable; hence, any one who takes care of horses; a groom; -- so called because the innkeeper formerly attended to this duty in person.
3. (Railroad) The person who takes charge of a locomotive when it is left by the engineer after a trip.
She said his previous experience included three years as a hostler, moving trains about the yard in New Haven.