The word "怎么着" is formed through the fusion and conventionalization of the common interrogative phrase "怎么" (how/what) with the colloquial particle "着", which here acts as a reinforcing suffix that adds a tone of immediacy, insistence, or confrontation to the question. This combination, originating in Northern Mandarin dialects, evolved from a flexible syntactic phrase into a fixed lexical unit where the original grammatical function of "着" is bleached, and the whole term functions as a single, idiomatic expression for challenging or pressing someone (e.g., "What are you going to do about it?"). Its formation is essentially a process of lexicalization, where a frequently used sequence of words coalesces into a new word with a specific, often more emphatic, pragmatic force.