1 an ethical theory that treats self-interest as the foundation of morality.
2 systematic selfishness.
3 self-opinionatedness.
4 = EGOTISM.
Derivatives:
egoist n. egoistic adj. egoistical adj.
Etymology: F eacutegoiumlsme ult. f. mod.L egoismus (as EGO)
Useful english dictionary. 2012.