The Chinese word "口无遮拦" is formed by sequentially combining four characters: 口 (mouth), 无 (without), 遮 (to cover), and 拦 (to block). Literally, it describes a mouth that lacks covering or obstruction, which metaphorically conveys the meaning of speaking without restraint or being bluntly outspoken. The formation directly links these characters to create a compound idiom where the subject (口) is modified by the predicate (无遮拦) to express the concept of unfiltered speech.