(a) Contract of Insurance means the agreement evidenced by endorsement of the credit instrument by the Commissioner or his duly authorized representative and includes the terms, conditions and provisions of this subpart and of the National Housing Act.

(b) Insured mortgage means a mortgage which has been insured by the endorsement of the credit instrument by the Commissioner.

(c) Mortgage means such a first lien upon real estate and other property as is commonly given to secure advances on, or the unpaid purchase price of, real estate under the laws of the State, district or territory in which the real estate is located, together with the credit instrument or instruments, if any, secured thereby. In any instance where an operating loss loan is involved, the term shall include both the original mortgage and the instrument securing the operating loss loan.

(d) Mortgagee means the original lender under a mortgage, its successors and such of its assigns as are approved by the Commissioner, and includes the holders of the credit instruments issued under a trust indenture, mortgage or deed of trust pursuant to which such holders act by and through a trustee therein named.

(e) Mortgagor means the original borrower under a mortgage and its successors and such of its assigns as are approved by the Commissioner.

(f) Project Mortgage means a blanket mortgage insured under section 213 of the Act, covering a group of not less than five single-family dwellings.