- 1 a person who watches someone or something According to observers, the plane exploded shortly after takeoff. To the casual observer (= someone who does not pay much attention), the system appears confusing. Most art forms require a contribution from the observer. Thesauruswitnessobserver onlooker passerby bystander eyewitnessThese are all words for a person who sees something happen.witness a person who sees something happen and is able to describe it to other people; a person who gives evidence in a court of law:Police are seeking witnesses to the accident.observer a person who watches something happen:According to observers, the election was peaceful and fair.onlooker a person who watches something that is happening but is not involved in it:A crowd of onlookers gathered at the scene of the accident.passerby a person who is going past someone or something by chance, especially when something unexpected happens:Police asked passersby if they had witnessed the robbery.bystander a person who is near and can see what is happening when something such as an accident or a fight takes place:Three innocent bystanders were killed in the crossfire.eyewitness a person who has seen a crime or an accident and can describe it afterwardPatterns a(n) witness/observer/onlooker/passerby/bystander/eyewitness sees something a(n) observer/onlooker/passerby/bystander witnesses something
- 2 a person who attends a meeting, lesson, etc. to listen and watch but not to take part A team of officials was sent as observers to the conference.
- 3 a person who watches and studies particular events, situations, etc. and is therefore considered to be an expert on them a celebrity observer