noun (n)

• an act of honor or courteous recognition(noun.communication)

  Synonym:
  salute
  

  source: wordnet30
• (usually plural) an acknowledgment or expression of good will (especially on meeting)(noun.communication)

  Synonym:
  greeting
  

  source: wordnet30
• word of greeting used to begin a letter(noun.communication)

  source: wordnet30
• The act of saluting, or paying respect or reverence, by the customary words or actions; the act of greeting, or expressing good will or courtesy; also, that which is uttered or done in saluting or greeting.(noun)

  source: webster1913