adequate vs mediocre

adequate

det
  • A sufficient amount of; enough. 

adj
  • Equal to or fulfilling some requirement. 

mediocre

noun
  • A person of minor significance, accomplishment or acclaim; a common and undistinguished person. 

  • A member of a socioeconomic class between the upper ranks of society and the agricultural workers. 

adj
  • Having no peculiar or outstanding features; not extraordinary, special, exceptional, or great; of medium quality, almost always with a negative connotation. 

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