Both stems have become full verbs in Modern French: déjeuner "to have lunch" and dîner "to dine". Furthermore, déjeuner does not derive directly from je desjun (< *disi(ēi)ūnō, with total loss of unstressed -ēi-). Instead, it comes from desjeüner, based on the alternative form je desjeün (< *disiē(i)ūnō, with loss of only -i-, likely influenced by jeûner "to fast" < jeüner < je jeün "I fast" < iē(i)ūnō: iē- is an initial rather than intertonic so the vowel -ē- does not disappear).
