Someone who is informed knows about a subject or what is happening in the world. 见多识广的; 了解情况的
adjective [原级]有知识的,了解情况的;有根据的,可靠的;明智的,有见识的
When journalists talk about informed sources, they mean people who are likely to give correct information because of their private or special knowledge. 有根据的 (消息来源)