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 ...

, the property of a solid body to resist deformation, which is sometimes referred to as rigidity *

Structural rigidity In discrete geometry and mechanics, structural rigidity is a combinatorial theory for predicting the flexibility of ensembles formed by rigid bodies connected by flexible linkages or hinges. Definitions Rigidity is the property of a structu ...

, a mathematical theory of the stiffness of ensembles of rigid objects connected by hinges *

Rigidity (electromagnetism) In particle physics, rigidity R is a measure of the resistance of a particle to deflection by magnetic fields, defined as the particle's momentum divided by its charge. For a fully ionised nucleus moving at relativistic speed, this is equivalent t ...

, 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 rigid body, also known as a rigid object, is a solid body in which deformation is zero or negligible, when a deforming pressure or deforming force is applied on it. The distance between any two given points on a rigid body rema ...

, 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 transformation ...

, in mathematics, a rigid transformation preserves distances between every pair of points *

Rigidity (chemistry) Rigid or rigidity may refer to: Mathematics and physics *Stiffness, 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 rig ...

, 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 muscle ...

, 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 and the tendency to perseverate, which is the inability to change habits and modify concepts a ...

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

Other uses

Real rigidity In macroeconomics, rigidities are real prices and wages that fail to adjust to the level indicated by equilibrium or if something holds one price or wage fixed to a relative value of another. Real rigidities can be distinguished from nominal rigi ...

, and

nominal rigidity In economics, 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 tim ...

, the resistance of prices and wages to market changes in macroeconomics * Ridgid, a brand of tools {{disambiguation