self-centered; egoistic; selfish
Describes a person or behavior that prioritizes oneself over others, often with a negative connotation. Used as a な-adjective.
He has a self-centered way of thinking.
Selfish behavior hurts the people around you.
利己主義 names a principle or ideology of putting one's own interests first, while 自己中心的 is an adjective describing a self-centered personality or behavior, not a belief system.