How to define Poverty

There are three different ways to determine who is actually "poor" or not. The first way uses an income guide based on size of family. This method recognizes the composition of a family and decides if what a family makes is acceptable for the number of members in a household.Then there is the "supplement Poverty measure." this involves the government and how they help those with low incomes. Lastly there is the  consumption method that focuses on what the people in the household actually spend. Either way, is there ever a clear line to who faces poverty and who doesn't? And is it fair how the government helps those who are right below the poverty line yet not the people barely above? Think about it.