Mass. Gen. Laws ch. 146 § 1
The following words as used in this chapter, unless a contrary meaning is specifically prescribed or the context otherwise requires, shall have the following meanings:
"Board", the board of boiler rules appointed under section ten of chapter twenty-two.
"Boiler", A closed pressure vessel in which water is heated, steam is generated, steam is superheated or any combination thereof, under pressure or vacuum for use externally to itself by the direct application of heat from the combustion of fuel, or from electricity or nuclear energy. The term "Boiler" shall include fired units for heating or vaporizing liquids other than water where these units are separate from processing systems and are complete within themselves.
"Chief", the chief of inspections of the department of fire services.
"Department", the department of fire services.
"District engineering inspector", an inspector of the division.
"Division", the division of inspection of the department of fire services.
"Inspector", a district engineering inspector of the division of inspection of the department of fire services, or an inspector of an insurance company authorized to insure steam boilers in the commonwealth.
"Pressure Vessel", A vessel in which the pressure is obtained from an external source or by the application of heat from an indirect source or from a direct source, other than a vessel defined as a "Boiler" in this section.
Mass. Gen. Laws ch. 146, § 1