The word 背叛 is formed by combining two characters, each contributing a vivid physical metaphor to convey the abstract idea of betrayal. The first character, 背, originally depicts the back or spine, here meaning "to turn one's back on" or to act contrary to. The second, 叛, is built from the components for "half" (半) and "a knife/sword" (刀 in its ancient form), historically evoking the image of splitting or rebellion. Thus, together they create a compound image of literally turning one's back and cutting ties, powerfully encapsulating the act of forsaking allegiance.