even though vs however

even though

conj
  • Although; though; despite or in spite of the fact that. 

however

conj
  • But, yet, though, although. 

  • In any way in which. 

  • Regardless of the way in which. 

adv
  • How ever: an emphatic form of how, used to ask in what manner. 

  • In contrast. 

  • To whatever degree or extent. 

  • Nevertheless; yet, still; in spite of that. 

  • In any way that one likes or chooses; in a haphazard or spontaneous way. 

How often have the words even though and however occurred in a corpus of books? (source: Google Ngram Viewer )