bystander
n. countable B2 Upper Intermediate US //ˈbaɪˌstændɝ// UK //bˈaɪstændɐ// by·stander
n. a person who is standing near an event or accident but is not taking part in it. You are just watching what is happening.
n. a person who is present at an event or incident but does not take part in it. Often used in the context of accidents, crimes, or public disturbances.
An innocent bystander was hurt during the street fight.
Several bystanders watched the rescue attempt from the sidewalk, but none of them knew how to help.
The psychological phenomenon known as the bystander effect suggests that individuals are less likely to offer help to a victim when other people are present.
From by- + stander. Compare passerby.
Usage
Often paired with the adjective 'innocent' to emphasize that the person had no connection to the conflict.