noun (n)

• a sign posted in a public place as an advertisement(noun.communication)

  Example:
  A poster advertised the coming attractions.
  

  Synonym:
  bill, card, notice, placard, posting
  

  source: wordnet30
• someone who pastes up bills or placards on walls or billboards(noun.person)

  Synonym:
  bill poster, bill sticker
  

  source: wordnet30
• a horse kept at an inn or post house for use by mail carriers or for rent to travelers(noun.animal)

  Synonym:
  post horse, post-horse
  

  source: wordnet30
• A large bill or placard intended to be posted in public places.(noun)

  source: webster1913
• One who posts, or travels expeditiously; a courier.(noun)

  source: webster1913