“Wumbology, the study of ‘wumbo’. It’s first grade, Spongebob!”
Wumbo is the change, which once implemented would lift the hard-coded limit on how much money can be locked up in a lightning channel at a given time. As of Jan 2019 this is limited to a value roughly corresponding to US$ 600. The name Wumbo was chosen in November 2018 at a "summit" in Adelaide, Australia, where Lightning’s top developers gathered.