The word "写字" is formed by combining the character "写", meaning to write, which is a simplified form derived from the traditional character "寫", with the character "字", meaning character, which itself is composed of the radical "宀" (roof) and the component "子" (child), historically conveying the concept of nurtured literacy. Together, they create a compound where the action of writing is applied to the object of characters, resulting in the meaning "to write characters".