Holding one's own self-interest as the standard for decision making. / Having regard for oneself above others’ well-being.

the quality of being selfish; the condition of putting one's own interests before those of others.

(proscribed) comparative form of selfish: more selfish

plural of selfishness

Synonym of rational egoism (“theory espoused by Ayn Rand”)

A DNA sequence that spreads by forming additional copies of itself within the genome and makes no specific contribution to the reproductive success of its host organism.

plural of selfish gene

(evolutionary theory) The gene regarded as the primary driver and beneficiary of the evolutionary process.

(proscribed) superlative form of selfish: most selfish

In a selfish manner; with regard to private interest only or chiefly.