As used in this chapter, the following words and terms shall mean unless the context shall indicate otherwise: “Authority” means an authority created under the provisions of § 15.2-5702 or, if any such authority shall be abolished, the entity succeeding to the principal functions thereof. “Federal agency” means the United States of America and any department or bureau thereof, and any other agency or instrumentality of the United States of America heretofore established or which may be established hereafter. “Park” means public parks and recreation areas as the terms are generally used.