This paper stems from two different perspectives—that of the Latinists, and that of the Romanists—upon the concept of ‘Vulgar Latin’, perspectives that have given rise to a friendly debate between Pierre Flobert and Eugeniu Coșeriu. We try to highlight a number of lexical elements that are common to Classical and Vulgar Latin. Our approach leans upon the idea (found also with Maria Iliescu) that the diachronic vision upon language must take into consideration the sum of the histories of the words that belong to that language. Observing several lexical items excerpted from texts belonging to various epochs of the Latin culture (Archaic, Classical, Late), to various authors (Cicero, Vergilius, etc.), and to authors whose works contain elements of spoken language (Plautus, Petronius, etc.), from works of a high level language (epics, discourse, dissertation), and from texts with strong marks of orality (comedies, letters, sermons), we were able to see the semantic evolution of several Latin words preserved in the Romance languages. Our conclusion endorses the notion of a “common language”, which explains the parallel existence of words like casa, pauimentum, caballus, formosus, uetulus, auricula, gula, bucca, manducare, incendere, draco both in the Classical and Vulgar Latin, without notable differences.