There are several synonyms for the phrase "being one obligation". Some examples of these synonyms include having a responsibility, being duty-bound, having a commitment, being obligated, or having an imperative. Each of these synonyms implies a sense of duty or obligation to fulfill a certain task or responsibility. Being one obligation suggests that there is a singular task or responsibility that must be fulfilled, while these synonyms may encompass a broader range of duties or commitments. Ultimately, each of these synonyms emphasizes the importance of meeting one's obligations and fulfilling one's responsibilities.