The Collaborative International Dictionary of English v.0.48:

Endeavor \En*deav"or\, n. [Written also endeavour.]
   An exertion of physical or intellectual strength toward the
   attainment of an object; a systematic or continuous attempt;
   an effort; a trial.
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         To employ all my endeavor to obey you.   --Sir P.
                                                  Sidney.
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   To do one's endeavor, to do one's duty; to put forth
      strenuous efforts to attain an object; -- a phrase derived
      from the Middle English phrase "to do one's dever" (duty).
      "Mr. Prynne proceeded to show he had done endeavor to
      prepare his answer." --Fuller.

   Syn: Essay; trial; effort; exertion. See Attempt.
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