To secretly listen to and record someone's phone calls or electronic communications without their permission.
From 'wire' (telephone line) plus 'tap' (to intercept). The term emerged in the early 1900s as telephone technology spread and law enforcement needed terms for secret surveillance.
The FBI wiretapped Martin Luther King Jr. extensively, trying to discredit him with private conversations. When exposed, it revealed how surveillance has always been a political tool, not just a security measure.
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