Scottish Gaelic from Old Celtic "red king".

When Gaelic was a forbidden language in Scotland, most Gaelic-speakers converted their names to a closely sounding English one. Thus Ruairidh was usually Anglicized as Roderick although there is no real common source for the two names.

The unrelated Welsh name Rhydderch is also Anglicized as Roderick so is classed here as a lesser synonym.