Webster’s Revised Unabridged Dictionary · 1913
Rigidity
Ri·gid′i·ty (rĭ·jĭd′ĭ·ty̆), n. [L. rigiditas: cf. F. rigidité. See Rigid.] 1. 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.
2. Stiffness of appearance or manner; want of ease or elegance. Sir H. Wotton.
3. Severity; rigor. [Obs. orR.] Bp. Burnet.
Syn. — Stiffness; rigidness; inflexibility.