Possibly from the Welsh place name Cardigan (Ceredigion) or a rare modern coinage.
Cardis may come from the Welsh place name Cardigan, linked to Ceredigion, though it could also be a modern coinage. That ambiguity gives the name a slightly place-based, slightly invented quality. It sounds compact and distinctive, with a strong final consonant that keeps it from feeling too soft. Cardis has the kind of rare, surname-like energy that can feel quietly modern while still hinting at older geographic roots.