the honourable obligation that is the responsibility of those of high rank; in American English this often includes the expectation of benevolent actions such as helping those less fortunate
Noblesse oblige is the idea that people with advantages, for example those of a high social class, should help and do things for other people. They did so without hope of further profit and out of a sense of noblesse oblige. the idea that people who belong to a high social class should behave in a kind and generous way towards people of a lower social class