When it comes to expressing the concept of "art one's obligation," there are several synonyms available that can be used interchangeably to convey the same meaning. One such synonym is "one's duty" which implies that something is required of someone as a matter of moral or legal obligation. Another synonym could be "one's responsibility" which denotes a duty or obligation to act in a particular way to fulfill some obligation. Additionally, phrases such as "moral imperative," "compulsion," or "responsibility to perform" may also be used to express the same concept that one has a strong obligation or duty to carry out. Ultimately, the exact synonym used largely depends on the context in which it is being used.