bystander

/ˈbaɪˌstændər/
noun
  1. A person who is present at an event or situation but does not take part in it.
    • The police asked any bystanders if they had witnessed the robbery.
    • He was just an innocent bystander who got caught in the middle of the argument.
    • A bystander called 911 when she saw the accident happen.
Antonyms
What does "bystander" mean? | whatsthatwordmean | whatsthatwordmean