adjective (a)

• giving careful attention to detail; hard to please; excessively concerned with cleanliness(adj.all)

  Example:
  A fastidious and incisive intellect.
  Fastidious about personal cleanliness.
  

  Antonym:
  unfastidious
  

  source: wordnet30
• having complicated nutritional requirements; especially growing only in special artificial cultures(adj.all)

  Example:
  Fastidious microorganisms.
  

  Synonym:
  exacting
  

  source: wordnet30
• Difficult to please; delicate to a fault; suited with difficulty; squeamish; as, a fastidious mind or ear; a fastidious appetite.(adjective)

  source: webster1913