verb

• (transitive) To undo or open a lock or something locked by, for example, turning a key, or selecting a combination.
  "I unlocked the door and walked in."
• (transitive) To obtain access to something; to meet the requirements of a security or protection system.
  "I unlocked the dictionary article so I could edit it."
• (transitive, mobile telephony) To configure (a mobile phone) so that it is not bound to any particular carrier.
• (transitive) To disclose or reveal previously unknown knowledge or potential.
  "The discovery of a clue unlocked the mystery."

noun

• (video games) An initially hidden feature that is made available to reward the player for some achievement.
  "The other unlocks, like a grenade launcher or a sniper's steady ability, didn't fit into my playstyle."