91.630.  Definitions. — Wherever used in sections 91.620 to 91.770, unless a different meaning clearly appears from the context:

  (1)  The term "board" shall mean the board of public works set up by sections 91.620 to 91.770 to control, manage and operate the undertakings herein described.

  (2)  A "defense area" shall constitute the territory within a radius of fifty miles of a camp, encampment, cantonment, fort, depot, or other establishment of the Armed Forces of the United States of America within which not less than ten thousand persons are stationed, except the territory contained in any county now or hereafter having a population of not less than two hundred thousand nor more than four hundred thousand inhabitants.

  (3)  The term "government" shall mean the United States of America, or any department, agency or instrumentality thereof now in existence or hereafter created.

  (4)  The term "governing body" shall mean the bodies and boards, by whatever names they may be known, charged with the governing of a municipality as herein defined.

  (5)  The term "municipality" shall mean any county, school district, city, town, village, township, road district, public water supply district or drainage district located in whole or in part within a defense area, except any county now or hereafter having a population of not less than two hundred thousand nor more than four hundred thousand inhabitants and also except any school district, city, town, village, township, road district, public water supply district or drainage district or other political subdivision or public corporation located within any such county.

  (6)  The term "undertaking" shall include the following undertakings or any combination of two or more of such undertakings, whether now existing or hereafter acquired or constructed:  Hospitals, water systems, and sewer systems (both sanitary and storm); together with all parts of any such undertaking and all appurtenances thereto and equipment therefor including, without limiting the generality of the foregoing, lands, easements, rights in land, water rights, contract rights, franchises, approaches, dams, reservoirs, sewage disposal plants, intercepting sewers, trunk, connecting and other sewer and water mains, filtration works, pumping stations and equipment.