Quoting Wiktionary, which might or might not be right: "From French dent-de-lion ‎(“lion's tooth”), also in Late Latin dēns leōnis. The term has since died out in French (except in Swiss French), but compare Spanish diente de león, Italian dente di leone, Norwegian løvetann, Portuguese dente-de-leão, and also German Löwenzahn, all having the same literal meaning." Being a French speaker, I can say that I have never heard dent-de-lion used, but it would be an appropriate name for the flower.