IPA: //ˌiːɡoʊˈɪstɪkli//
KK: /ˈiːɡoʊˌɪstɪkli/
In a way that shows concern only for oneself and one's own interests, often disregarding others' needs or feelings.
She acted egoistically, putting her own desires above the needs of her friends.
Egoistically → It is formed from "ego" (from Latin *ego*, meaning I or self) and "-istically" (a suffix used to form adverbs indicating a manner or characteristic). The word "egoistically" means in a manner that is self-centered or focused on oneself.
Think of 'ego' as representing the self, and remember that 'egoistically' describes acting in a way that is centered around oneself.