a person or thing that loans.
something, as an automobile or appliance, that is lent especially to replace an item being serviced or repaired.
Origin of loaner
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
1884, "one who lends," agent noun from loan (v.). Meaning "a thing loaned" especially in place of one being repaired, is from 1926.
Online Etymology Dictionary, © 2010 Douglas Harper