The term “false etymology” refers to the imaginative reconstruction of the origin and history of a word, widely circulating among laymen despite its lack of any scientific foundation. Based on a corpus of false etymologies of Italian, French and Spanish words (and occasionally of other Romance languages and dialects), the article attempts a definition and classification of the phenomenon, according to the classes of words affected and the techniques by which words are analyzed, as far as both their forms and meanings are concerned. A reflection on the social function of false etymologies is also provided, as well as considerations on how false etymologies originate and spread in contemporary societies.