onlooker
UK: ˈɒnˌlʊkə | US: ˈɑːnˌlʊkər
n. a person who watches an event or activity without participating in it; a spectator.
The word "onlooker" combines "on" (from Old English "on," meaning "upon") + "look" (from Old English "lōcian," meaning "to see") + the agent suffix "-er." It literally means "one who looks upon," reflecting the passive role of observing without involvement. The term emerged in the early 19th century, emphasizing the distinction between active participants and passive observers.
The onlooker recorded the accident with his phone.
A crowd of onlookers gathered around the street performer.
She felt like a mere onlooker in her own life.
The police asked the onlookers to step back.
His role as an onlooker gave him a unique perspective on the debate.