Section 25. As used in sections twenty-six to twenty-seven, inclusive, the following words shall have the following meanings, unless a different meaning clearly is indicated from the context:

''Annual income'', a person's or family's gross annual income less such reasonable allowances for dependents, other than spouse, and for medical expenses, as determined by the department.

''Housing development area'', any blighted open area, or any decadent area, or any substandard area, as respectively defined in section one of chapter one hundred and twenty-one B, as determined by the department.

''Low income persons and families'', those persons and families whose annual income is equal to or less than the maximum amount which would make them eligible for housing assistance pursuant to chapter one hundred and twenty-one B, as determined by the department.

''Low and moderate income rental housing project'', a rental housing project which shall be rented to (a) low income persons or families; (b) moderate income persons or families; or (c) other persons or families whose annual rental for the unit to be occupied shall be at least equal to the rentals charged for similar units in the market area, as determined by the department so that any benefit to the tenants who are not low or moderate income persons or families derived from the assistance provided to sponsors of rental housing projects pursuant to section twenty-seven will be at most incidental to and no greater than is necessary for achieving proper housing for low and moderate income persons and families.

''Market rate rental'', the rental which would be be charged if the project received no financial assistance pursuant to section twenty-seven, as determined by the department.

''Moderate income persons or families'', those persons and families, other than low income persons or families, whose annual income is less than the amount necessary to enable them to obtain and maintain decent, safe and sanitary housing without the expenditure of over twenty-five per cent of such income for housing expenses, including the provision of heat, electricity, or hot water, as determined by the department.

''Rental housing project'', the construction or rehabilitation of two or more dwelling units in which no less than twenty-five per cent of the dwelling units shall at all times during the period of any contract entered into pursuant to section twenty-seven be rented to persons and families who are, at the time of initial occupancy, of low income. Rental housing project shall also include such cooperative housing projects as have the characteristics of rental housing rather than homeownership by reason of limitations on equity realizable by shareholders on resale, or such other features as may be defined in guidelines published for the program.

''Sponsors'', any individual, firm, association, partnership, including limited partnerships, trust, corporation, and other legal entities, including public bodies as well as natural persons.