As used in this chapter, the following terms shall have the meanings indicated:
A private housing or dwelling unit where the owner, tenant or occupant is engaged in keeping two or more boarders, not related to him by blood or marriage, for a part of a day or longer period, and in serving food to lodgers, under expressed contract or agreed rate of payment.
A private housing or dwelling unit open to the public where the owner, tenant or occupant is engaged in keeping two or more guests for a part of a day or a longer period under expressed contract or agreed rate of payment.
A private dwelling unit where the owner, tenant or occupant is engaged in keeping two or more lodgers, not related to him by blood or marriage, for a part of a day or longer period under expressed contract or agreed rate of payment.