To gain access through hacking. It can also describe a situation where you are able to log into another person's email/computer/username/etc. simply because they left their password on the 'remember always' setting
I got haccess into the CIA national database and found that military-grade toilet seats really do cost upwards of $20,000
My brother left his computer on, so I got haccess into his facebook and made all of his info 'i like dick'.
A combination of the words access and hack, or h4x0r. This would be used by 1337 persons preventing a h4x0r from cheating them in a video game, such as Counter Strike.
h4x0r: I'm gonna h4x0r into his comput0r and get that n00b!
teh 1337 player: No! h4x355 (haxess) denied! lolllolololololollolol!!!!1!1