verb (v)

• open the lock of(verb.contact)

  Example:
  Unlock the door.
  

  source: wordnet30
• set free or release(verb.contact)

  source: wordnet30
• become unlocked(verb.change)

  Example:
  The door unlocked from the inside.
  

  Antonym:
  lock, lock
  

  source: wordnet30
• To unfasten, as what is locked; as, to unlock a door or a chest.(verb)

  source: webster1913