noun
alternative name; alias
General term for a name used in place of one's real name; can be a pseudonym, alias, or alternate designation.
彼はネット上で替え名を使っている。
He uses an alias online.
noun
assumed name in a brothel
Historical term for a pseudonym used by a customer in a red-light district to maintain anonymity.
江戸時代、遊郭では客が替え名を名乗ることがあった。
In the Edo period, customers in the pleasure quarters would sometimes give assumed names.
noun
Used for performers, such as actors or entertainers, who adopt a professional name different from their real name.
その俳優は本名ではなく替え名で活動している。
That actor works under a stage name, not his real name.
Compound of 替え (substitute) + 名 (name). The exact historical derivation is uncertain, but the term has been used since at least the Edo period.