x_{1} (li; tensor with units of kg×m^{2}) is the moment of inertia/angular inertial-mass/rotational inertia of object x_{2} around axis/point of reference x_{3} in basis/coordinate system x_{4}.

Physics is all about expressing the same thing in different ways in order to gain new insight about it. There are other ways to express a mathematical quantity which is equivalent to this one (much as gravitational charge and inertial mass are mathematically mutually equal but not conceptually identical).