Section 1. As used in this chapter, the following words, shall unless the context otherwise requires, have the following meanings:—

''Bank'', a savings bank, co-operative bank, or trust company subject to the supervision of the commissioner of banks.

''Capital'', (1) the sum of the capital stock, surplus account and undivided profits of a savings bank or a co-operative bank which has converted to a stockholder form of corporation, a subsidiary banking institution of a mutual holding company as defined in chapter 167H or a trust company as defined in section 1 of chapter 172; (2) the sum of the surplus account of a mutual form savings bank governed by chapter 168 or a mutual form co-operative bank governed by chapter 170. The commissioner, in his discretion, may further define or permit adjustments to the capital accounts of a bank necessary to effect the purposes of this chapter.

''Commissioner'', the commissioner of banks.

''Real estate'', land or property, without geographic limitation, including improved land with a dwelling, owner occupied or unoccupied dwellings, unimproved land, farmland, a unit of a condominium, shares of stock issued by a co-operative housing corporation, industrial and commercial property, leasehold interests created in air rights over land, and any other interest in land; but a loan secured by real estate shall include a loan on a leasehold under a lease which does not expire for at least 5 years beyond the maturity date of the loan.