Stuborn or Stubborn: How To spell?

The word Stuborn is misspelled against Stubborn, an adjective meaning "Firm as a stub or stump; stiff; unbending; unyielding; persistent; hence, unreasonably obstinate in will or opinion; not yielding to reason or persuasion; refractory; harsh; -- said of persons and things; as, stubborn wills; stubborn ore; a stubborn oak; as stubborn as a mule."