Commercial Motor Vehicle (CMV)
A vehicle meeting federal thresholds for weight, passenger capacity or hazardous materials, which brings it under federal motor carrier safety rules.
The classification matters because it decides which rules apply. Once a vehicle is a commercial motor vehicle, obligations follow around driver qualification, inspection, maintenance records and hours.
Public fleets are often surprised by which of their vehicles qualify. Refuse packers, dump trucks, large buses, apparatus and heavier service trucks commonly do, and a fleet that thinks of itself as a light-duty municipal operation may still have a regulated subset sitting inside it. Exemptions for government operations exist in places and vary, which makes this a question to confirm against the actual rules and the state adoption of them rather than to assume either way.