The word 'unturned' is a straightforward English formation built upon the core verb 'turn,' which entered English from Old French 'torner' or 'turner,' itself from Latin 'tornare' (to turn on a lathe), derived from 'tornus' (lathe), a borrowing from Greek 'tornos' (lathe, circle). The negative prefix 'un-,' of ancient Germanic lineage, is one of the most productive in English for creating opposites. The adjectival suffix '-ed' attaches to the verb to describe the resultant state. Thus, the literal meaning "not having been turned" is preserved in its modern abstract sense, most commonly used in the idiomatic phrase "to leave no stone unturned," implying a state of thoroughness where nothing remains undisturbed or unexamined.

Structure: un (not) + turn (to rotate) + ed (adjective suffix) - un: A prefix of Germanic origin (Old English) meaning "not," used to form negatives. - turn: A verb of Latin and Greek origin, via Old English and Old French, meaning "to rotate, change direction." - ed: A suffix of Germanic origin (Old English) used to form adjectives from verbs, indicating a state or condition.