Weight
In modern scientific usage, weight and mass are fundamentally different quantities: mass is an intrinsic property of matter, whereas weight is a "force" that results from the action of gravity on matter: it measures how strongly the force of gravity pulls on that matter. However, in most practical everyday situations the word "weight" is used when, strictly, "mass" is meant. For example, most people would say that an object "weighs one kilogram", even though the kilogram is a unit of mass.
Charmed baryons
All particles decay by the strong force. Typically this mean the emission of a pion as it decays down to the comparatively stable . Thus their masses are not usually measured directly, but in terms of their mass differences, m()−m(). This is experimentally easier to measure precisely, and theoretically easier to predict, than the absolute value of the mass.