bystander

an interested bystander studying the form.

bystanders were leering at the nude painting.

involved the bystanders in his dispute with the police.

The police asked bystanders about the accident.

Bystanders bared their heads as the funeral procession passed.

A crowd of confounded bystanders stared at the appalling wreckage.

Objective To study the role of bystander effect in the cytocidal activity of TK/GCV against tumor cells.

A bystander responded immediately to the victim's obvious need for help), or to an involuntary emotional response (