n
1 person who observes 观察者; 遵守者; 评论者
*an observer of nature 自然界的观察家
* a poor observer of speed restrictions 不遵守速度限制的人.
2 person who attends a conference, lesson, etc to listen and watch but not to take part （会议、课堂等的）观察员, 旁听者
*an observer at a summit conference 高峰会议上的观察员
* send sb along as an observer 派某人作观察员.

n[C]
someone who regularly watches or pays attention to particular things, events, situations etc
observer of
　an observer of nature
　political observers
　Observers are predicting a fall in interest rates.
someone who attends meetings, classes, events etc to check what is happening
　The UN sent observers to the peace talks.
　Independent observers monitored the elections.
someone who sees or looks at something
　reports from observers at sea and on dry land
casual observer
(=someone looking at something but not very carefully)
　A casual observer would have guessed his age at 70.