Could Latin virgo:, virginis fit into this same scheme? *bHrgWHen- > expected *firben-, perhaps turned into *virgen- after influence of vir or viridis.
JS Lopes
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I think that development is too unlikely, although I must admit I have no plausible explanation of _virgo:_. In my opinion the best candidates for Italic derivatives of *bHergWH- are Old Latin _ferctum_ 'type of sacrificial cake' (later _fertum_) and Oscan _fertalis_ 'ceremonies associated with erecting jovilae', but there are formal difficulties. One would expect zero-grade *forctum 'purified', so that cannot be the meaning of the cake's name. The act of purification might have been expressed by an /u/-stem *ferctus, but one would then expect something like *ferctuom 'cake associated with purification' and (in Latin) *ferctua:lia 'ceremonies of purification'. Considering these difficulties, derivation of the attested words from *bHergWH- is a long shot.
DGK