Mortgage holder, e.g.

• One whose property is held
• One whose property is claimed legally
• One whose property is claimed, legally
• Borrower on property
• Name on a property deed, maybe
• Holder of a collateral loan
• One with a mortgage, e.g.
• One subject to a mortgage
• One with a claim against him

Wiktionary Word definitions in Wiktionary
n. (context legal English) One who has right of possession of goods but not right of property; the registered owner.