For the purposes of this chapter, the following words and phrases shall have the meanings respectively ascribed to them by this section:
A vehicle operated upon the streets of the City as a carrier of passengers for hire, to such destination as directed by them.
A section of a public street or public place set apart for the exclusive use of a limited number of public hacks or taxicabs, when such section is distinctly marked as such by a metal sign attached to a stanchion on the curb or other conspicuous place or by clearly visible marks upon the surface of the street or public place.