Define "low information" however you'd like, but I would generally say voters who make irrational decisions that are based on little to no information.
"Information" is subjective since supporters of each candidate likely believe most of the other candidate's supporters are low information with only a small group of "evil/cynical" high information voters who know their preferred candidate is deeply flawed but support for personal gain.
Questions for comments:
Would the United States be better off if "low information" voters (magically) didn't vote?
Is the term "low information" inherently discriminatory or is there a clear and concise definition?
Supposing "low information voters" make democracy dysfunctional, what's a better solution for governance?