nudius.

From Proto-Indo-European *nu (“now; well; and”) + diūs, reflecting the original nom.sg. of diēs (“day”) that was later remodelled on the accusative. The former component cognate to Latin num (interrogative particle), nunc (“now”), nūper (“lately, recently”); its length is uncertain, since the original short vowel of PIE appears to have undergone lengthening in numerous daughter languages, with both Sanskrit and Greek showing both variants. The original nominative also surfaces in me-diū̆s-Fidius (“so help me God”, interjection) as well as in diurnus; whether it retained the length of the ū cannot be established. The uncertainty over etymological vowel lengths is compounded by the fact that both the scansions nŭdĭū̆s (with anceps third syllable) and nūdĭŭ(s) (with s-loss or iambic shortening) are possible in all the occurrences except one, where nū- is required.