There's some great Poker PC games out now with excellent AI opponents. I have "World Class Poker", "DD Tournament Poker 2", and "Poker Academy". I'd recommend them all for practicing without losing money and no donkfests like at the online play money tables.
I've seen some people refer to live poker as playing in offline mode. Guess the implication is that they are going against the flow of where most people play. So instead of online, they are offline.