Refers to the act of setting aside one's own interests for the sake of others or a greater cause. Often used in formal or ethical contexts, and strongly associated with the phrase 滅私奉公 (selfless devotion to public duty).
I participated in volunteer activities with a spirit of selflessness.
His attitude of selfless devotion to public service impressed many people.
selfless devotion to public duty
Compound of 滅 (destroy, extinguish) and 私 (self, private). The exact historical derivation is uncertain, but the term is conventionally associated with the Confucian-influenced ideal of subordinating personal interests to the collective.