Egoistic (adjective)

1. Relating to or having an excessive interest in oneself.
2. Concerned with one's own interests or welfare to the exclusion of those of others.

Origin:

From the latin word "ego" meaning "i" + "istic" meaning "pertaining to".

Examples:

1. He was egoistic and always put his own needs above those of others.
2. She was known for her egoistic behavior and always put herself first.
3. His egoistic tendencies led to him being disliked by his coworkers.
4. An egoistic person only cares about himself and his own interests.
5. The egoistic leader made decisions that only benefited himself and his inner circle.