The word "一鳞半爪" is formed by combining four characters: "一" (one), "鳞" (scale), "半" (half), and "爪" (claw), where each character retains its literal meaning to create a metaphorical image. The phrase directly depicts seeing only a single scale or half a claw, which together convey the idea of incomplete or fragmentary information, thus forming an idiom that signifies scattered bits or a partial view.