noun (n)

• something or someone that causes anxiety; a source of unhappiness(noun.cognition)

  Synonym:
  concern, vexation, worry
  

  source: wordnet30
• pain in the head caused by dilation of cerebral arteries or muscle contractions or a reaction to drugs(noun.state)

  Synonym:
  cephalalgia, head ache
  

  source: wordnet30
• Pain in the head; cephalalgia.(noun)

  source: webster1913