Unless the context otherwise indicates, the following definitions shall be used in the interpretations and construction of this chapter. Words used in the present tense include the future and the future, the present; the singular number shall include the plural and the plural, the singular; the word "structure" includes the word "building"; the word "lot" includes the word "plot"; the word "occupied" includes the words "designed or intended to be occupied"; the word "used" shall include the words "arranged, designed, constructed, altered, converted, rented, leased or intended to be used"; the word "shall" is mandatory and not optional, and the word "may" is permissive.