1. Someone who literally CAN NOT survive without getting on tumblr at least once a day.
2. Someone who thinks everyone will die in a horrible tragedy if they do not log on at least once a day to post indie pictures, emo quotes, and naked Harry Potter pictures.
3. Generally, just someone who is fuckawesome.
1. Dude that guy is pelting the waitress with shrimp because she won't give him wi-fi access so he can get on tumblr. Total tumbladdict.
2. If I don't get on tumblr right this second, Y2K is going to occur belatedly! No, I'm NOT a tumbladdict! I'm serious!
3. Guy: I have a tumblr.
Girl: Please have sex with my vagina now, you are a glorious tumbladdict please.