The definition which is the unit when making physics develop, it's important to be consistent. When handling of the unit isn't consistent when combining a physics system different in more than 2 in particular, it's natural for a calculation result to become inaccurate. The value based on the specific unit as well as that will be divergent and be that it'll be a zero, and the peculiar point which is seemingly in an equation shows, and the price becomes unsettled over the whole equation, and I can also get a meaningless solution at all. When I close using "the weight" as "definition of the mass", the price will be in the state of "by the mass, zero" seemingly at space, and is a zero for the item by which mass m is multiplied, and the price emits the item by which mass m is in the denominator. A handling mistake of the mass and the weight is the boring funny story, but present-day physics has no conclusive evidence in which I don't make a similar mistake. I divide a definition of the unit among the main subject as "a unit, its own definition" "definition of measurement of the unit", think and propose the most suitable element the respective definitions should have. I aim at a multi-purposed definition by it's in shoes of a neutron, and changing the mind about a definition in time.