informant
n
1 person who gives information 提供消息或情报的人
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.
2 (linguistics 语言) native speaker of a language who helps a scholar make an analysis of the language 发音合作人(为语言学者分析语言提供资料的说本地话的人).