obscure vs unclear

obscure

adj
  • Unknown or uncertain; unclear. 

  • Dark, faint or indistinct. 

  • Difficult to understand. 

  • Not well-known. 

  • Hidden, out of sight or inconspicuous. 

verb
  • To hide, put out of sight etc. 

  • To render obscure; to darken; to make dim; to keep in the dark; to hide; to make less visible, intelligible, legible, glorious, beautiful, or illustrious. 

unclear

adj
  • Not having a clear idea; uncertain. 

  • Not easy to see or read; indecipherable or unreadable. 

  • Ambiguous; liable to more than one interpretation. 

  • Not clearly or explicitly defined. 

verb
  • To undo the process of clearing. 

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