A charter party carrier of passengers means every person (an individual, a corporation, association, joint stock association, and partnership, their lessees) engaged in the transportation of a group of persons, who under a single contract, have acquired the use of a motor bus to travel together as a group within the state of Washington.

An excursion service carrier of passengers means every person (an individual, a corporation, association, joint stock association, and partnership, their lessees) engaged in the transportation of persons for compensation from points of origin to any other locations within the state of Washington and returning to that origin.