speaker in WordNet English dictionary

1. electro-acoustic transducer that converts electrical signals into sounds loud enough to be heard at a distance
   loudspeaker  speaker  speaker unit  loudspeaker system  speaker system 
   
2. someone who expresses in language; someone who talks (especially someone who delivers a public speech or someone especially garrulous)
   "the speaker at commencement"; "an utterer of useful maxims"
   speaker  talker  utterer  verbalizer  verbaliser