noun (n)

• someone who expresses in language; someone who talks (especially someone who delivers a public speech or someone especially garrulous)(noun.person)

  Example:
  The speaker at commencement.
  

  Synonym:
  talker, utterer, verbaliser, verbalizer
  

  source: wordnet30
• electro-acoustic transducer that converts electrical signals into sounds loud enough to be heard at a distance(noun.artifact)

  Synonym:
  loudspeaker, loudspeaker system, speaker system, speaker unit
  

  source: wordnet30
• the presiding officer of a deliberative assembly(noun.person)

  Example:
  The leader of the majority party is the Speaker of the House of Representatives.
  

  source: wordnet30
• One who speaks.(noun)

  source: webster1913