A passenger refers to a person who travels in a vehicle, whether public or private, but is not the driver or operator. The term broadly applies to anyone transported from one place to another by another person or service.
Originally, the word passenger aligned closely with wayfarer, meaning a traveler journeying on foot or by any means.
In contemporary English, a passenger is:
There were two passengers in the car in addition to the driver.
Author’s summary: The word passenger describes a person who rides in any means of transport but doesn’t operate it, emphasizing the role of being carried rather than controlling.