though vs whether

though

conj
  • Despite the fact that; although. 

adv
  • Used to intensify statements or questions; indeed. 

  • Despite that; however. 

whether

conj
  • Indicates doubt between possibilities (usually with correlative or). 

  • Introduces a disjunctive adverbial clause qualifying the main clause (with correlative or). 

  • Without a correlative, introduces a simple indirect question. 

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