Speaker (noun)

1. A person who speaks, especially in public or in a formal setting.
2. A device that converts electrical signals into sound.
3. The presiding officer of a legislative assembly or a public meeting.
4. A person who delivers a speech or lecture.

Origin:

Late middle english: from old french speaker, from latin spaciator "an umpire", from spatiari "make peace", from spatium "space".

Examples:

1. The speaker was asked to address the crowd.
2. He bought a new speaker for his car's sound system.
3. The speaker of the House of Representatives was impeached.
4. The keynote speaker was a renowned scientist.
5. She was nervous but a fantastic speaker.