approval vs barrier

approval

noun
  • Something mailed by a seller to a collector to match their stated interests; the collector can approve of or return the item. 

  • An expression granting permission; an indication of agreement with a proposal; an acknowledgement that a person, thing, or event meets requirements. 

  • An expression of favorable acceptance and encouragement; a compliment that also condones. 

barrier

noun
  • A separation between two areas of the body where specialized cells allow the entry of certain substances but prevent the entry of others. 

  • A martial exercise of the 15th and 16th centuries. 

  • The lists in a tournament. 

  • A structure that bars passage. 

  • An obstacle or impediment. 

  • A node (in government and binding theory) said to intervene between other nodes A and B if it is a potential governor for B, c-commands B, and does not c-command A. 

  • A boundary or limit. 

verb
  • To block or obstruct with a barrier. 

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