It started with looking up North African terms for 'rainbow' in Berber and Arabic. I confirmed that one Arabic expression is similar to the hypothetical Etruscan expression *Tluscval arcam that might lie behind the aforementioned abbreviation tlusc arc inscribed on the Piacenza Liver where its religious significance might have something to do with a role as messenger between sky and earth. That expression is qaws al-māʔ 'bow of the water', spoken in the Maghreb. Another rainbow expression in Berber, 'bride of the jackal', led me to the Roman Virgo Caelestis, the Latin name given to the Carthaginian goddess of the sky. To the delight of my humour bone, this then led me straight to something I hadn't come across before: Cloācina, goddess of the sewers and of the Cloāca Maxima (ie. The Great Drain of Rome). Yes, the Romans had a goddess of sewers. It's very amusing but also a natural product of a polytheistic religion that maintains that all things great and small, glorious and foul, must have a deity governing it. Stinky as this tale is, something perverse within me needed to dig further.
The name of Cloācina immediately takes hold of my attention because it could be quite easily an Etruscan name. Many Etruscan names end in -na, including those of divine epithets (eg. Aracuna 'Of the hawks', a byname of the death goddess Vanth). In fact, the Cloāca Maxima herself was the ingenious invention of Etruscan engineers to efficiently take away much of the daily filth naturally produced by its inhabitants in the city. Etruscans were master architects and founders of Rome before the Latin-speaking population became dominant so it naturally makes me wonder if the name Cloācīna and the term cloāca 'sewer' could be hidden Etruscan lexical items.
Immediately when looking it up, one will find an ample number of etymologists connecting it with cluēre 'to cleanse, purify'. Perfectly sensible. But... Latin has two homophones here and the other meaning of this verb is 'to hear, be spoken of, be said'. This latter verb is without a shred of doubt traced back to Proto-Indo-European *ḱleu- but does the other verb truly go back to PIE *ḱleuh₁- as often claimed by Indoeuropeanists? Etymological dictionary of Latin and the other Italic languages by Michiel de Vaan lends doubt under the heading cloāca:
"Since an original sequence *klowV- would have yielded *clau- (at least, in pretonicSo given the limited cognate set (limited to Western IE languages only) and dubious attempts to derive these words using IE-based grammar, there seems to be room for another hypothesis from outside of Indo-European. Is it possible that Etruscan had a verb *cluva 'to cleanse, to purify' that led to an adjective *cluvaχ 'clean, pure'? Through *cluvaχ, we could obtain *Cluvacuna /ˈkluwəkʊˌna/ '(She) of the pure' leading to Latin Cloācīna. We'd also have the basis for Latin cloāca 'sewer', now to be understood as a loanword and nothing to do with Proto-Indo-European. The instance of cluce in the Liber Linteus could be translated as a perfective 'has purified' (< ? earlier *cluvace), a verb to be expected in a ritual text.
position), Vine 2006a: 2l7f. posits an adj. *kleuH-o- 'clear, clean' from which a
factitive pr. *kleuH-eh₂-ie/o- > *klewāje/o- > *klowā- could have been derived. This
verb might be preserved in the Servius gloss cloare, although its reliability is often
doubted. From *clowā-, the noun cloāca can then be explained. WH and Rix argue
that cluō may have been invented by Plinius to explain Cluācīna but it might also
derive from *cluwere < *klowere < *kleuH₁-e/o-. For the root, Derksen (fthc.) reconstructs *ḱlh₃-u-, whereas Rasmussen posits *ḱleh₁-u-. If one accepts such a root structure, the ablaut *kle/ou(H)- of Latin must represent a secondary full grade based on a zero grade *kluH₁- < *klHu-C-. The short vowel of Greek κλύζω remains unexplained under any account."