Definition of black hat
: a hacker who infiltrates a computer system for malicious purposes (as to disable a website or uncover secret information) In one segment … Assange reflects on his work as a black hat hacker in the early 1990s, recalling wistfully how he and others hacked into the Pentagon's Security Coordination Center. — Kim Zetter — compare white hat
First Known Use of black hat
Seen and Heard
What made you want to look up black hat? Please tell us where you read or heard it (including the quote, if possible).