flavus.

Uncertain. Perhaps from Proto-Italic *flāwos. The term is often compared with Proto-Germanic *blēwaz and Proto-Celtic *blāwos, though it is difficult to reconstruct a single pre-form underlying all of these terms. De Vaan suggests that, should the Germanic and Celtic comparison be rejected, it is possible to reconstruct a pre-form *bʰl̥h₁wós. Alternatively, Schrijver suggests a connection with flōs, perhaps indicating a pre-form *bʰleh₃-wo-, which could explain the Germanic and Celtic forms if a delabialization of *bʰleh₃- to *bʰleh_(1/2)- is presumed. Such a development is, however, highly speculative. Kroonen argues that the Germanic and Italo-Celtic forms may be unified under a single ablauting PIE u-stem *bʰléh₁-us ~ *bʰl̥h₁-wόs. However, Matasović suggests that the only possible means of connecting the Germanic to the Italo-Celtic terms would be to posit a vrddhi form *bʰlēh₂wo-, which he considers to be an ad hoc and speculative assertion.