As described in historical dictionaries

Patronymica Britannica (1860)

RIORDAN. An old Irish siu-name, variously written O'Rierdon, Reyrdon, Reardon, Reardcn, &c.

Lower, Mark A (1860) Patronymica Britannica: a dictionary of the family names of the United Kingdom. London: J.R. Smith. Public Domain.


Origin: Celtic

Region of origin: British Isles

Country of origin: Ireland

Religion of origin: Christian

Language of origin: Gaelic

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