Populism is a loosely defined term which seems to refer to actions taken by any group within a society which is fed up with conditions affecting them, low wages, unemployment, refugees, immigration and so on.
It is used to describe the reasons for Brexit in the UK, terrorism/racism/immigrants and unequal income distribution in the US, and refugees and related conditions in countries such as France, the Netherlands, Italy and even Germany.
In Canada, according to Wikipedia, populist movements describe the Social Credit and the Reform Party in Alberta, Creditistes, the Union Nationale and PQ in Quebec, the federal Liberal party under Prime Ministers Mackenzie and Laurier, labour parties leading up to the CCF and NDP, and support for various premiers of Ontario.
This seems to be rather all inclusive referring to any time when a group in society becomes activated and organizes politically. It merely describes contemporary political conditions. A recent case of populism today would be Ford Nation in Toronto, where one segment of the city feel that they are taxed for the benefit of another. The Ford brothers used this to their political advantage.
It does not seem to be a useful term unless the reasons for it are given.