For the purpose of this chapter the following definitions shall apply unless the context clearly indicates or requires a different meaning.
   COST.  Includes the expense of the survey, the preparation of the tax roll, notices, advertising, printing, financing, legal, engineering, construction and condemnation and all other costs incidental to the making of the improvement.
   IMPROVEMENT.  Any public betterment the cost of which may be defrayed by special assessment as authorized by the Charter.
(`73 Code, 12.201, § 1.101)