Hello, I'm asking this question for a practical reason (I'm trying to contribute to Wiktionary) but also because it seems to me the question is worthwhile, perhaps even fascinating (depending on one's sensibility ). According to the Gran diccionari de la llengua catalana, the origin of Catalan quelcom 'something' is not clear, but it probably developed from Latin quidcumque: quelcom [s. XIV; probablement del ll. quidcum(que) 'qualsevol cosa', a través d'un *quecom, analitzat com què o com, d'on queucom i, per ultracorrecció, quelcom] In the light of the above entry, the development of quel- is quite exceptional, and what led to it was a series of analogies and reinterpretations. (French quel- < Latin quālis, and its Occitano-Romance counterpart is qual-, var. quau-). The Occitan language possesses the form quicòm 'something', which can be traced back to Latin quidcumque more easily. And, indeed, Loís Alibèrt ( 1976: 530) indicates its origin as Latin quīcumque, which seems quite plausible except that quīcumque is the plural masculine (Acc., Nom., and Voc.) of quiscumque, while the Acc./Nom./Voc. quidcumque (with its Nom./Voc. variant, as indicated in the Wiktionary, quiccumque) is singular neuter and, therefore, more plausible as a source for quicòm 'something'. There's also Occitan quaucòm, also meaning 'something' (Alibèrt 1976: 529), which coexists with quicòm in Vivaro-Alpine (and probably also in varieties of Languedocien), and its Gascon variant quaucom (Champlain  2010: 198). When I discovered it, I thought it would be closer etymologically to Catalan quelcom than quicòm is. Should we proceed on that assumption, we'd have to account somehow for the difference between quelcom and quaucòm (the quau- part being pronounced [kaw] or [kɔw], depending on the dialect). Maybe it's worth mentioning there exists another synonym of the above words (one very wide-spread dialectally), namely quauquarren (quauqua ren) (Alibèrt 1976: 528). I reconstructed the origin of quauquarren as: De qualqua (deu latin quālis + quam, acusatiu femenin de quī) + ren (deu latin rem, acusatiu de rēs) on the basis of these entries (GDLC): qualque: [s. XIII; de qual i que] qual: [s. XII; del ll. qualis, adj. i pron. interrogatiu, 'tal com; com; de quina mena'] que: [s. XII; com a relatiu, del ll. quem, acus. de qui; com a conjunció, del quid interrogatiu, amb aportacions del quia causal; com a comparatiu, d'una confusió de quem i la conj. quam] re and my pretty basic knowledge of Latin. It seems to me there might not have been substantial analogy operating between qualqua ren and what was to become quaucòm alone, but there are also words like Occitan qualqu'un (var. quauqu'un) 'somebody' (~ Catalan qualcú). Yet, there is also Latin quāliscumque (> French quelconque), which seems to be the perfect candidate for the source of quaucòm, so perhaps there's no need to go as far as to explain the origin of quaucòm by morphological leveling and contamination? If quaucòm / quaucom descends from quāliscumque, then quelcom and quicòm quite likely are cognates, while quaucòm and quicòm are not. What do you think? Alibèrt, Loís.  1976. Dictionnaire occitan-français d'après les parlers languedociens. Tolosa: Institut d'Estudis Occitans. (http://mertyl.free.fr/dico/alibert.pdf) (darrièra consulta: 21 julh 2012). Chaplain, Éric.  2010. Dictionnaire gascon (béarnais)—français ancien et moderne. (3na edicion; 1ra edicion 2002, 2na edicion 2008, 3na edicion 2010.) Cressé: PyréMonde.