endeavor (n.) Look up endeavor at Dictionary.com
early 15c., "pains taken to attain an object," literally "in duty," from phrase put (oneself) in dever "make it one's duty" (a partial translation of Old French mettre en deveir "put in duty"), from Old French dever "duty," from Latin debere "to owe" (see debt). One's endeavors meaning one's "utmost effort" is from late 15c.
endeavor (v.) Look up endeavor at Dictionary.com
c.1400, from phrase put in dever (see endeavor (n.)). Related: Endeavored; endeavoring.