The study provides a critical etymological discussion on the common nouns frequently referred to in the literature as Celtic. Distinctions are drawn between genuinely Celtic and dia-Celtic on the one hand, and in loco formations and migrant words on the other. The hitherto neglected Cisalpine formations show significant differences from North to South and East to West. Lexically, the agallicità label appears to apply more to the Emilia-Romagna than to Veneto and Grisons. Attempts to classify Romance dialects on the basis of the substrates should regard the Rhaeto-Romanic varieties and the Upper Italian varieties as a unity.