信賴（朝外）
把核心的「信賴感」朝外放：相信某個人、某樣東西、或某件事一定會發生、會成。
trust · noun · B2
Trust that a person or a thing is good and can be relied on.
信任、信心
核心畫面
Picture a firm feeling of trust — you lean your weight on someone or something and feel sure it will hold. The Latin root con-fidere means 'to trust fully'. From that one feeling of trust, the word branches in two directions: trust pointed OUTWARD (you trust a person, a thing, an outcome) and trust pointed INWARD (you trust yourself). A second, narrower branch comes from trust between two people: things told 'in trust', kept secret.
可以想成一種「放心去倚靠」的感覺：你把重量靠上去，相信它撐得住、不會塌。拉丁字根 con-fidere 就是「完全信…更多收起
可以想成一種「放心去倚靠」的感覺：你把重量靠上去，相信它撐得住、不會塌。拉丁字根 con-fidere 就是「完全信賴」。從這一份「信賴感」往兩個方向長：一個朝外（信任某個人、某樣東西、某個結果會成），一個朝內（信任自己做得到，也就是自信）。另外還有一條較窄的支線，來自人與人之間的信賴——「託付給你、請你保密」的那些話。From the word’s history
English confidence comes from Latin confidentia, from confidere 'to have full trust', con- (intensive) + fidere 'to trust' — the same fid- root as in faith, fidelity. The modern core 'a feeling of trust' sits right on that root, and 'self-confidence' is simply that trust turned toward oneself.
英文 confidence 來自拉丁文 confidentia，源於 confidere「完全信賴」：con-（加強語氣）＋ fidere「信賴」——和 faith（信仰）、fidelity（忠誠）是同一個 fid-（信）字根。現代的核心義「信賴的感覺」就直接坐在這個字根上，而「自信」不過是把這份信賴轉向自己。
Online Etymology Dictionary (etymonline.com), 'confidence' / 'confide'; Latin fidere 'to trust'.
Three branches
自信（朝內）
把同一份「信賴感」轉向自己：相信自己做得到、應付得來——對象從別人變成你本人。
self-confidence · noun · B2
The feeling that you can do things well and deal with situations.
自信
私下信賴、保密
這一族來自人與人之間的信賴：因為信得過你，才把話只說給你聽、託你保密。於是 confidence 從「信賴感」延伸到「被信賴而託付的私密話」本身。
in confidence · noun · B2
When you tell someone something in confidence, you tell it on the understanding that they will keep it secret.
保密、私下（告訴）
原始詞典資料4 筆記錄
以下是外部詞典記錄的用法，原文照列，我們還沒有寫成教學內容。上面的說明才是我們自己寫的；有些用法可能上面已經講過了。
confidencenoun/ˈkɒn.fɪ.dəns/
- 1
Self-assurance.
- He entered the ring with confidence.
- 2
A feeling of certainty; firm trust or belief; faith.
- She had confidence it would soon end.
- It is better to truſt in the Lord : then to put confidence in man. / It is better to truſt in the Lord : then to put confidence in Princes.
- 3
Information held in secret; a piece of information shared but to thence be kept in secret.
- In the course of these confidences it became quite plain to me I had been represented to the wife of the high dignitary, and goodness knows to how many more people besides, as an exceptional and gifted creature - a piece of good fortune for the Company - a man you don’t get hold of every day.
- 4
datedBoldness; presumption.
資料來源：英文維基詞典 English Wiktionary（CC BY-SA 4.0）。 原文照列，未經改寫。