Moment of inertia
From AMS Glossary
moment of inertia
For a system of point masses, the sum of the product of each mass and the square of its perpendicular (minimum) distance from a given axis.
For a continuous mass distribution, the sum becomes an integral. In general, moment of inertia is a tensor because moments of inertia are different for three orthogonal axes. Moment of inertia plays a similar role in angular momentum to that which mass (inertia) plays in linear momentum.
Goldstein, H. 1959. Classical Mechanics. Ch. 5.