'arianrhod' originates from Welsh, specifically the elements 'arian' and 'rhod', where 'arian' meant 'silver' and 'rhod' meant 'wheel'.

'arianrhod' is attested in Middle Welsh sources (notably the Mabinogion) as the proper name 'Arianrhod' and has been preserved into modern English usage as the name of the mythological figure.

Initially the compound literally implied 'silver wheel' (likely a poetic reference to the moon or a celestial wheel); over time it became primarily a proper name for the mythic figure with those poetic associations.