Your conscience is your inner voice that tells you what's right and wrong. It's like having a built-in moral compass.
When someone says "follow their conscience", they usually mean to listen to their own sense of what's right or fair. People might also talk about making decisions with their conscience, which means considering how it will make them feel, not just thinking about the facts or logic. This word is often used in discussions about ethics and morality. If someone says "I couldn't do that - it wouldn't be right" they're probably speaking from their conscience.
The moral sense of right and wrong, chiefly as it affects one's own behaviour.
Example: Your conscience is your highest authority.
