noun (n)

• the part of the day between noon and evening(noun.time)

  Example:
  He spent a quiet afternoon in the park.
  

  source: wordnet30
• a conventional expression of greeting or farewell(noun.communication)

  Synonym:
  good afternoon, good morning, morning
  

  source: wordnet30
• The part of the day which follows noon, between noon and evening.(noun)

  source: webster1913