Merriam-Webster Collegiate Dictionary - sophist

 noun  Etymology: Latin ~a, from Greek ~es, literally, expert, wise man, from sophizesthai to become wise, deceive, from sophos clever, wise  Date: 14th century  1. philosopher  2. capitalized any of a class of ancient Greek teachers of rhetoric, philosophy, and the art of successful living prominent about the middle of the fifth century B.C. for their adroit subtle and allegedly often specious reasoning  3. a captious or fallacious reasoner