Origin: 1350–1400; Middle English endeveren, from the phrase putten in devoir to make an effort, assume responsibility; compare Anglo-French se mettre en deveir.See en-1, devoir
Related forms
en·deav·or·er; especially British, en·deav·our·er, noun
early 15c., lit. "in duty," from phrase put (oneself) in dever "make it one's duty" (a partial translation of O.Fr. mettre en deveir "put in duty"), from O.Fr. dever "duty," from L. debere "to owe" (see debt). One's endeavors meaning one's "utmost effort" is from late 15c.