someone who sees an event and reports what happened
同义词：witness, witnesser
informant例句
Police hurried to the address supplied by their informant, only to learn that their bird had flown less than an hour before.
警察急忙赶到告密者提供的地址处，只获悉他们要捉的人一小时不到前已逃走了。
A person, especially an informant, who communicates something.
传递信息的人传达某事的人，尤指密告者
The journalist did not want to reveal the identity of his informant.
那个新闻工作者不想透露消息提供人的身分。
informant详细解释
in.form.ant n.（名词） One that gives information.通知者：提供消息的人One who informs against others; an informer.告密者：检举他人的人；告密的人One who furnishes linguistic or cultural information to a researcher.为研究者提供语言或文化方面信息的人
