The Chinese idiom "户枢不蠹" is formed by sequentially combining the characters for "door" (户), "hinge" (枢), "not" (不), and "worm-eaten" (蠹). It literally constructs the phrase "a door hinge does not get worm-eaten", deriving from the observable fact that constant motion prevents decay. The formation follows a straightforward grammatical structure where "户枢" acts as the subject, "不" as the negator, and "蠹" as the verb, together conveying a metaphorical idea through this direct composition.