पूर्ण शक्ति वाले किसी एक शासक द्वारा चलाई जाने वाली सरकार को क्या कहा जाता है?

Choose the most suitable 'one word' for the given expression: 'A person who does not believe in the existence of God or gods'

Which one-word term is used to describe an animal or person that prefers to live, move, or associate in groups rather than in isolation, exhibiting a natural inclination for companionship?