The 2018 Supreme Court decision on Murphy v. National Collegiate Athletic Association brought not only a change in the United States commercial gambling landscape, but also considerable speculation across public forums about whether expanded sports gambling causes new, distinct, and greater harm than existing legal forms of gambling. This commentary brings into the focus that the definition of this form of gambling has recently begun to shift without a theoretical basis or empirical evidence. To bring evidence to bear, there is a need for a precise operational definition of sport gambling and greatly clarity to the questions that can drive knowledge generation.