(?470-399 BC) a Greek philosopher from Athens, who was the teacher of Plato and whose ideas are known from Plato's writings. He encouraged people to think carefully about ideas before accepting them and developed a method of examining ideas according to a system of questions and answers in order to find out the truth. This is known as the Socratic method or dialectic. The Greek authorities disapproved of his ideas and methods, and said he was a bad influence on young people. They forced him to kill himself by drinking hemlock, a powerful poison.
Definition from the Longman Dictionary of Contemporary English Advanced Learner's Dictionary.