Sir William David Ross, a deontological philosopher, proposed two concepts: "prima facie duty" and "actual duty" in his innovative theory to solve the problem of the conflict between duties which Kant faced. Conflict is only related to prima facie duties, but in actual duty, the doer always notice only one duty. However, Ross tried to offer other interpretations and use other term for "prima facie duty" by which he intended to fulfill his aims and objectives, because he was worried that it would be misunderstood. He offers five interpretations for "prima facie": conditional duty, particularistic duty, inclination towards duty, balance, and responsibility. The present paper deals with the semantics of "prima facie duty" in Ross's ethics, using an analytical approach.