The Collaborative International Dictionary of English v.0.48:

Endeavor \En*deav"or\, v. t. [imp. & p. p. Endeavored; p. pr.
   & vb. n. Endeavoring.] [OE. endevor; pref. en- + dever,
   devoir, duty, F. devoir: cf. F. se mettre en devoir de faire
   quelque chose to try to do a thing, to go about it. See
   Devoir, Debt.] [Written also endeavour.]
   To exert physical or intellectual strength for the attainment
   of; to use efforts to effect; to strive to achieve or reach;
   to try; to attempt.
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         It is our duty to endeavor the recovery of these
         beneficial subjects.                     --Ld. Chatham.
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   To endeavor one's self, to exert one's self strenuously to
      the fulfillment of a duty. [Obs.] "A just man that
      endeavoreth himself to leave all wickedness." --Latimer.
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