Two possibilities include:
- From Etruscan 𐌌𐌖𐌈 (muθ, “pit, mundus”).
- From Proto-Indo-European *mH₂nd- (“to adorn”) and cognate with Old High German mandag (“joyful, happy, dashing”). Possibly also conflated in the sense of "clean, neat" with Proto-Indo-European *muH₂-, *meuH₂- (“to wash, wet”).
mundus (genitive mundī); m, second declension
- the world, universe, heavens
- a toilet/dress (of a woman)
- a decoration, an ornament
mundus m (feminine munda, neuter mundum); first/second declension
- clean, pure; neat
- nice, fine, elegant, sophisticated
- decorated, adorned