English 'pseudonym' from Greek 'pseudṓnymon' (false name), from 'pseudḗs' (false) + 'ónyma' (name), from PIE *h₁nómn̥ (name).
A fictitious name, especially one used by an author; a pen name.
From Greek 'pseudṓnymon' (ψευδώνυμον, bearing a false name), the neuter of 'pseudṓnymos' (falsely named), composed of 'pseudḗs' (ψευδής, false, lying, untrue) + 'ónyma' (ὄνυμα), the Aeolic and Doric dialect form of the Attic 'ónoma' (ὄνομα, name). The first element comes from 'pseúdesthai' (to lie, to speak falsely), of uncertain PIE origin. The second element, 'ónoma,' is from PIE *h₁nómn̥ (name), one of the most stable roots in Indo-European: it yields Latin 'nōmen' (name) → English 'nominal,' 'nominate,' 'noun'; Sanskrit
The PIE root *h₁nómn̥ (name) is one of the most consistent words across Indo-European: English 'name,' Latin 'nōmen' (→ noun, nominate), Greek 'ónoma' (→ synonym, anonymous), Sanskrit 'nāman,' Irish 'ainm,' Russian 'imya' — all from the same source. The '-onym' family includes 'synonym' (same name), 'antonym' (opposite name), 'anonymous' (without name), 'homonym' (same name but different meaning), and 'acronym' (tip-name).