The etymology derives the noun from a meteorological verb. The cloud is the "snowing one" or the "raining one". Here νείφω is translated as "to rain", this may be not from Philoxenus but from later authors: in fact, it is not in Orion either, who has Νέφος. οἷον νεφάος, τὸ ἐστερημένον φωτός. ἢ παρὰ τὸ νήφειν. οὕτω Φιλόξενος (νήφειν is an iotacising spelling), but is found in late sources like the Pseudo-Zonaras (see Parallels). Anyway, this etymology relies on a metonymic relationship between cloud and rain or snow coming from it. The alternation between [ei] in νείφω and [e] in νέφος is justified thus by Philoxenus (fr. 464): δέος· παρὰ τὸ δείω δέος, <ὡς> νείφω νέφος. Herodian reverses the derivational direction and derives νείφω from νέφος (Peri Orthographias, Lentz III/2, p. 554: ἐκ τούτου οὖν τοῦ νέφος γίνεται νέφω καὶ πλεονασμῷ τοῦ ι νείφω "from this nephos comes the verb *nephō and, through addition of the [I], neiphō", see νείφω / νέφος): Herodian's etymology is of a mimetic type, that is, clouds (A) are the source of rain or snow (B), therefore the word νέφος "cloud" (A') is the etymon of the word "to snow" (νείφω, B'), whereas Philoxenus' etymology is purely linguistic in so far as Philoxenus' etymological method starts from verbs as a rule, and here also. His explanation seems to have been fairly standard in classrooms as it is often repeated to justify other etymologies (see Parallels).