The word 失陪 is formed by combining two characters: 失, which carries the meaning of "to lose" or "to be lacking", and 陪, which means "to accompany" or "to keep someone company". Together, they create a conceptual image of "lacking in accompaniment" or "failing to stay with you", which is directly and politely used to express the speaker's need to excuse themselves from a person's company. It functions as a humble and fixed phrase of departure.