"to circumvent security and break into (a network, computer, file, etc.), usually with malicious intent"
Just because they didn't impress you by finding a side channel timing attack for the password hashing algorithm used by Yahoo, doesn't make it any less of a hack.
Why spend millions investing in a network of computers to break encryption, when the key can be gained far more easily with a $20 tire wrench applied with sufficient force to the DBA's knee caps?
When Sarah Palin's "personal" email was hacked during the 2008 election, the attacker used her Wikipedia page and recovery questions.[0]
[0]: http://nypost.com/2008/09/19/dem-pols-son-was-hacker/