Someone who devotes all their free time to Tumblr.

Frequently browsing tags related to their desires, and never pursuing them.
Janet: She spends all day on tumblr looking at fitness posts, talking about all the weight she's going to lose. But she hasn't exercised in 3 weeks!

John: Yeah she's a total tumblrbum
by weedlord360 November 12, 2015
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