Polar Vortex = the latest term for winter cold snap...for us Canadians...cold is a relative term for us...once our second winter skin is on, we are still wearing a sweater by the time everyone else has long been wearing full parkas...our blood has evolved the equivalent of antifreeze in our veins.
It's not a "winter cold snap"; it's the coldest air in the northern hemisphere which typically stays at the north pole, getting shunted to the eastern half of the US. It's not something that typically happens. It's not a new term, it's a scientific reality. Both poles have the coldest air on Earth for obvious reasons which contain normally stationary cyclones that typically don't retreat that far from the poles.