Other forms: blackmails, blackmailed, blackmailing
Blackmail is demanding money by threatening to reveal somebody's secret. Blackmail the witness, a blackmail attempt, subject to blackmail.
It is a serious criminal offence, and the threat need not be to reveal anything illegal — threatening to reveal something merely embarrassing is enough. Emotional blackmail is a figurative use meaning pressuring somebody by playing on guilt or affection. Note blackmailer, the person; extortion, which is the broader crime of obtaining anything by threat; and that in law the demand must be unwarranted, which is where most defences begin.
1nounblackmailDemanding money by threatening to reveal a secret.
“The blackmail went on for about eighteen months.”
synonyms: extortion
2verbthreatTo demand money by such a threat.
“He was blackmailed by somebody he had never met.”
blackmail is a crime of threat.
Also accepted in games: extortion
The mail here is an old Scots word for rent or tribute, unrelated to letters. Black mail was the protection money Border chiefs extracted from farmers, as against white mail, which was honest rent paid in silver.
Proto-Indo-European
*med-
English, today
blackmail
Built from
From black + mail (“a piece of money”). Compare Middle English blak rente (“a type of blackmail levied by Irish chieftains”). The word is variously derived from the tribute paid by English and Scottish border dwellers to border reivers in return for immunity from raids and other harassment. This tribute was paid in goods or labour, in Latin reditus nigri (“black mail”); the opposite is blanche firmes or reditus albi (“white rent”), denoting payment by silver. McKay derives it from two Scottish Gaelic - words blàthaich, pronounced (the th silent) bl-aich, "to protect" and màl (“tribute, payment”). He notes that the practice was common in the Scottish Highlands as well as the Borders.
Etymology from Wiktionary, CC BY-SA