noun (n)

• someone who leads a wandering unsettled life(noun.person)

  Synonym:
  bird of passage, roamer, rover
  

  source: wordnet30
• a computer program that prowls the internet looking for publicly accessible resources that can be added to a database; the database can then be searched with a search engine(noun.communication)

  Synonym:
  spider
  

  source: wordnet30
• One who wanders; a rambler; one who roves; hence, one who deviates from duty.(noun)

  source: webster1913