confidant

n. 心腹朋友, 知己

con.fi.dant

n.（名词）
One to whom secrets or private matters are disclosed.
知己：能向其倾吐秘密或私事的密友
A character in a drama or fiction, such as a trusted friend or servant, who serves as a device for revealing the inner thoughts or intentions of a main character.
密友：戏剧或小说中的人物，如作为可信赖的朋友或仆人，来揭露主角的内心思想和意图

来源：
French confident
法语 confident
from Italian confidente
源自 意大利语 confidente
from Latin cônfodôns cônfodent- [present participle of] cônfodere [to rely on] * see confide
源自 拉丁语 cônfodôns cônfodent- [] cônfodere的现在分词 [依赖于] *参见 confide