The word 坦白 is formed by combining two characters: 坦, which originally meant "flat" or "open ground" and by extension conveys a sense of "open" or "smooth", and 白, which means "white" and carries connotations of "clear", "pure", or "plain". Together, they create a vivid conceptual blend where the metaphorical openness and levelness of 坦 merges with the clarity and purity of 白 to express the idea of being "frank" or "to confess", that is, to make one's mind or situation open, clear, and unobstructed, as if laying something bare on flat, white ground.