The word "签字" is formed by combining two characters: "签", which historically depicts bamboo slips used for writing, symbolized by the bamboo radical (⺮) atop, and "佥" below, often contributing to sound and meaning related to endorsement; and "字", which represents a written character, composed of "宀" (roof) over "子" (child), evoking the idea of producing or giving birth to symbols. Together, these characters visually and conceptually merge the act of writing with bamboo-based tools and the creation of characters, resulting in the meaning of signing one's name or authorizing a document through written marks.