Rigid or rigidity may refer to:

Mathematics and physics

Stiffness Stiffness is the extent to which an object resists deformation in response to an applied force. The complementary concept is flexibility or pliability: the more flexible an object is, the less stiff it is. Calculations The stiffness, k, of a b ...

, the property of a solid body to resist deformation, which is sometimes referred to as rigidity * Structural rigidity, a mathematical theory of the stiffness of ensembles of rigid objects connected by hinges * Rigidity (electromagnetism), the resistance of a charged particle to deflection by a magnetic field *

Rigidity (mathematics) In mathematics, a rigid collection ''C'' of mathematical objects (for instance sets or functions) is one in which every ''c'' ∈ ''C'' is uniquely determined by less information about ''c'' than one would expect. The above statement doe ...

, a property of a collection of mathematical objects (for instance sets or functions) * Rigid body, in physics, a simplification of the concept of an object to allow for modelling *

Rigid transformation In mathematics, a rigid transformation (also called Euclidean transformation or Euclidean isometry) is a geometric transformation of a Euclidean space that preserves the Euclidean distance between every pair of points. The rigid transformations ...

, in mathematics, a rigid transformation preserves distances between every pair of points * Rigidity (chemistry), the tendency of a substance to retain/maintain their shape when subjected to outside force *(Modulus of) rigidity or shear modulus (material science), the tendency of a substance to retain/maintain their shape when subjected to outside force

Medicine

Rigidity (neurology) Spasticity () is a feature of altered skeletal muscle performance with a combination of paralysis, increased tendon reflex activity, and hypertonia. It is also colloquially referred to as an unusual "tightness", stiffness, or "pull" of muscles. ...

, an increase in muscle tone leading to a resistance to passive movement throughout the range of motion *

Rigidity (psychology) In psychology, rigidity or mental rigidity refers to an obstinate inability to yield or a refusal to appreciate another person's viewpoint or emotions characterized by a lack of empathy. It can also refer to the tendency to perseverate, which is the ...

, an obstacle to problem solving which arises from over-dependence on prior experiences

Other uses

* Real rigidity, and

nominal rigidity Nominal rigidity, also known as price-stickiness or wage-stickiness, is a situation in which a nominal price is resistant to change. Complete nominal rigidity occurs when a price is fixed in nominal terms for a relevant period of time. For exampl ...

, the resistance of prices and wages to market changes in macroeconomics *

Ridgid The Ridge Tool Company is an American manufacturing company that makes and distributes tools under the Ridgid brand name. The company was founded in 1923 in North Ridgeville, Ohio. In 1943, it relocated to its current location in Elyria, Ohio, ...

, a brand of tools {{disambiguation