The adjective egotistical describes the nature of egoism which is to be concerned in oneself or care about one’s personal desires rather than others.
Synonyms are egocentric, self-centered, self-absorbed, or narcissist.
The word origins from egoistic + al. The term ego is in a sense of “thinking subject” (in Latin ego means “I”). The first know use was in 1825-1835.
Those who are egotistical sometimes offend other people.
I do not want to be associated with egotistical people.
He has a very egotistical personality, so I broke up with him.