passerby
UK: ˌpɑːsəˈbaɪ | US: ˌpæsərˈbaɪ
n. a person who is walking past something, especially by chance
The word "passerby" is a compound formed from "passer" (derived from "pass," meaning to go by, with the agent suffix "-er") and "by" (meaning near or alongside). It literally means "one who passes by," reflecting its modern usage to describe someone who happens to be walking near a place. The term emerged in English as a straightforward combination of these elements, emphasizing the transient nature of the person's presence.
The accident was witnessed by a passerby who called for help immediately.
A kind passerby helped the lost child find their parents.
The artist drew inspiration from the faces of passersby on the busy street.
Police asked passersby if they had seen anything unusual.
The café’s outdoor seating is perfect for watching passersby.