unlock

Short definition from Wiktionary

Verb

1. 1
   To undo or open a lock or something locked by, for example, turning a key, or selecting a combination.
2. 2
   To obtain access to something; to meet the requirements of a security or protection system.
3. 3
   To configure (a mobile phone) so that it is not bound to any particular carrier.
4. 4
   To disclose or reveal previously unknown knowledge or potential.
5. 5
   To be or become unfastened or unrestrained.
6. 6
   To make available.
7. 7
   To undermine something that has control over a situation; to find a way to counter or oppose.

Noun

1. 1
   The act of unlocking something.
2. 2
   An initially hidden feature that is made available to reward the player for some achievement.