"one who grants a property as security for debt," 1580s, agent noun in Latin form from mortgage (v.). Native form mortgager is attested from 1630s. Barbarous mortgageor seems to be limited to legal writing.
we became mortgagors when the bank accepted our mortgage and loaned us the money to buy our new home
mortally
mortar
mortarboard
mortgage
mortgagee
mortgagor
mortician
mortification
mortified
mortify
Mortimer