(1):
(n.) One who is the mouthpiece of others; especially, one who presides over, or speaks for, a delibrative assembly, preserving order and regulating the debates; as, the Speaker of the House of Commons, originally, the mouthpiece of the House to address the king; the Speaker of a House of Representatives.
(2):
(n.) One who speaks.
(3):
(n.) A book of selections for declamation.
(4):
(n.) One who utters or pronounces a discourse; usually, one who utters a speech in public; as, the man is a good speaker, or a bad speaker.