The word 'unlock' is a transparent compound formed within English from native Germanic elements. The prefix 'un-', with its ancient Proto-Germanic root un-, carries a fundamental sense of negation or reversal. It is attached to the verb 'lock', which derives from the Old English loc, meaning an enclosure or fastening, and is related to the action of securing. The literal combination, "to reverse the action of locking," perfectly captures the word's core meaning. Over time, this concrete sense naturally extended into metaphorical uses, such as unlocking potential or information, following the logical path from physical release to figurative accessibility.

Structure: un (not, opposite action) + lock (fasten, secure) - un: A prefix of Germanic origin (Old English un-), meaning "not" or "the opposite of an action." It functions as a reversative or privative prefix. - lock: A verb of Germanic origin (Old English locian, "to fasten with a lock"), referring to the act of securing something.