Passerby (noun)

1. A person who passes by or goes by, especially on the street or road.
2. A person who is passing by or just happens to be near.
3. A person who is walking or travelling past a place or object.
4. An onlooker or spectator.
5. A person who walks or travels through an area, especially a busy one.

Origin:

18th century: from pass + by.

Examples:

1. The passerby stopped to watch the street performers.
2. The passerby didn't seem to notice the accident.
3. The passerby offered to help the lost child.
4. The passerby looked surprised by the sudden noise.
5. The passerby offered directions to the tourist.