stiffness

As an adjective rigid

is rigid.

As a noun stiffness is

rigidity or a measure of rigidity.

Stiffness is a related term of harshness.

As nouns the difference between stiffness and harshness

is that stiffness is rigidity or a measure of rigidity while harshness is the quality of being harsh.

Stiffness is a related term of sternness.

As nouns the difference between stiffness and sternness

is that stiffness is rigidity or a measure of rigidity while sternness is (uncountable) the state or quality of being stern.

As nouns the difference between stiffness and numbness

is that stiffness is rigidity or a measure of rigidity while numbness is absent or reduced sensitivity to cutaneous stimulation.

Rigor is a synonym of stiffness.

As nouns the difference between rigor and stiffness

is that rigor is while stiffness is rigidity or a measure of rigidity.

As nouns the difference between stiffness and pain

is that stiffness is rigidity or a measure of rigidity while pain is .

As an adverb pain is

towards, in/to the direction of.

As nouns the difference between tense and stiffness

is that tense is any of the forms of a verb which distinguish when an action or state of being occurs or exists while stiffness is rigidity or a measure of rigidity.

As a verb tense

is to apply a tense to.

As an adjective tense

is showing signs of stress or strain; not relaxed.

As nouns the difference between stiffness and softness

is that stiffness is rigidity or a measure of rigidity while softness is the quality of being soft.

As a noun stiffness

is rigidity or a measure of rigidity.

As an adverb rigidly is

in a rigid manner; stiffly.

As nouns the difference between stiffness and compressibility

is that stiffness is rigidity or a measure of rigidity while compressibility is the degree to which something is compressible.