A fictitious name used by an author to conceal his or her identity.
"Anonymity is a shield from the tyranny of the majority. It thus exemplifies the purpose behind the Bill of Rights, and of the First Amendment in particular: to protect unpopular individuals from retaliation—and their ideas from suppression—at the hand of an intolerant society. The right to remain anonymous may be abused when it shields fraudulent conduct. But political speech by its nature will sometimes have unpalatable consequences, and, in general, our society accords greater weight to the value of free speech than to the dangers of its misuse."
~ Supreme Court Justice John Paul Stevens
McIntyre v. Ohio Elections Comm’n 514 U.S. 334, 357 (1995)