Someone who is even better than a best friend, who's always there for you no matter what, and who understands you almost as well as you do yourself. And screw that "it's short for homosexual" crap you see on here. And it don't mean anything less just because white people use it too.
ninja can also be used the same, along with holmes.
homie number one: "my homie is the only person who doesn't judge what i do or say"
homie number two: "that's 'cause i'm your best ninja"