real name written backwards, 1867, from Greek ana "back" (see ana-) + onyme "name" (from PIE root *no-men- "name"). Properly anonym, but this has another sense in English.

c. 1600, "without a name;" 1670s, "published under no name, of unknown authorship," from Late Latin anonymus, from Greek anonymos "without a name," from an- "without" (see an- (1)) + onyma, Æolic dialectal form of onoma "name" (from PIE root *no-men- "name").