Stiffness definition

(1) Excessive sternness

"Severity of character"

"The harshness of his punishment was inhuman"

"The rigors of boot camp"

(2) The inelegance of someone stiff and unrelaxed (as by embarrassment)

(3) Firm resoluteness in purpose or opinion or action

"A charming host without any touch of stiffness or pomposity"

(4) The property of moving with pain or difficulty

"He awoke with a painful stiffness in his neck"

(5) The physical property of being inflexible and hard to bend