The compound adjective "worked-out" is a relatively modern formation, emerging from the productive pattern in English of combining a verb's past participle with an adverbial particle to create a descriptive state. The core verb "work" originates from the Proto-Germanic werkan, carrying the fundamental sense of "to do" or "to perform." The particle "out," from Proto-Germanic ūt, often denotes a conclusion or an external state. When combined, the literal sense of "brought out through work" or "worked to completion" evolved into its modern abstract meanings. For a plan or idea, it signifies it has been thoroughly developed and finalized. For a person or resource, it metaphorically extends to mean drained or exhausted, as if the internal effort or material has been fully expended and brought "out."

Structure: work (to perform labor) + out (to completion) - work: From Old English weorc, meaning "something done, deed, action, proceeding, business, military fortification." In this compound, it carries the sense of performing labor or mental effort. - out: From Old English ūt, meaning "out, without, outside." In this compound, it functions as an adverbial particle indicating completion, thoroughness, or exhaustion.