Rigidity

Webster's Dictionary of the English Language

·noun Severity; rigor.

II. Rigidity ·noun Stiffness of appearance or manner; want of ease or elegance.

III. Rigidity ·noun The quality or state of being rigid; want of pliability; the quality of resisting change of form; the amount of resistance with which a body opposes change of form;

— opposed to flexibility, ductility, malleability, and softness.