用秘密換錢或換服從
核心畫面最原本的形態：把柄是實在的秘密，交換的是錢或具體的服從。
threat to expose secrets · noun · C2
The act of trying to get money from someone, or make them do what you want, by saying you will tell other people their secrets.
勒索
核心畫面
One way to picture it: someone holds a thing that could hurt you — a secret, a proof, even your own guilt — and won't put it down. "Do what I want, or I let this out." The force is never in a fist; it is in what they are holding.
手上握著一樣會傷到你的東西，然後不放手——「你照我說的做，不然我就把它放出去。」重點不在暴力，而在那個被握住的把柄：…更多收起
手上握著一樣會傷到你的東西，然後不放手——「你照我說的做，不然我就把它放出去。」重點不在暴力，而在那個被握住的把柄：一個秘密、一段醜聞、一份證據，或者一份你欠對方的人情。對方不必動手，只要讓你一直感覺到那樣東西還在他手上，你就會照做。From the word’s history
Originally the tribute that English and Scottish border dwellers paid local chieftains for protection — mail here is an old word for rent or payment, black marking it as the illegitimate kind. From the start it named coercion-by-holding, not robbery.
這個字原本指十六世紀英格蘭與蘇格蘭邊境居民付給當地首領的「保護費」——mail 在此是古語的「租金、款項」，black 則與正當繳納的「白錢」相對，指這種被迫上繳的黑錢。也就是說，它從一開始就不是搶劫，而是「你付了才會平安」的持續脅迫——這正是現代用法裡那份「握著不放」的味道。
Wiktionary, "blackmail" (black + mail "a piece of money"; compare Middle English blak rente)
Two branches
用情緒與虧欠感施壓
把柄從外部的秘密換成內部的感受：握在對方手上的不再是證據，而是你的愧疚或不安，但「不照做就有代價」的結構完全一樣。
emotional coercion · noun · C2
The act of trying to make someone do what you want by making threats, or by making them feel guilty if they do not do it.
要挾
原始詞典資料7 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。
blackmailnoun/ˈblækˌmeɪl/
- 1
The extortion of money or favors by threats of public accusation, critique, or exposure.
- 2
Compromising material that can be used to extort someone.
- 3
BDSMlifestylesexualityCompromising material that can be used to extort someone.
- 4
archaicA form of protection money (or corn, cattle, etc.) anciently paid, in the north of England and south of Scotland, to the allies of robbers in order to be spared from pillage.
- 5
historicallawBlack rent; rent paid in corn, meat, or the lowest coin, as opposed to white rent, which was paid in silver.
blackmailverb/ˈblækˌmeɪl/
- 1
To extort money or favors from (a person) by exciting fears of injury other than bodily harm, such as injury to reputation, distress of mind, false accusation, etc.
- He blackmailed a businesswoman by threatening to expose an alleged fraud.
- 2
To speak ill of someone; to defame someone.
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。