individualism

Short definition from Wiktionary

Noun

1. 1
   The tendency for a person to act without reference to others, particularly in matters of style, fashion or mode of thought.
2. 2
   The moral stance, political philosophy, or social outlook that promotes independence and self-reliance of individual people, while opposing the interference with each person's choices by society, the state, or any other group or institution.
3. 3
   The doctrine that only individual things are real.
4. 4
   The doctrine that nothing exists but the individual self.