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 rigid objects connected by hinges *Rigidity (electromagnetism), the resistance of a charged particle to deflection by a magnetic field *Rigidity (mathematics), 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 preserves distances between every pair of points


*Rigidity (neurology), an increase in muscle tone leading to a resistance to passive movement throughout the range of motion *Rigidity (psychology), an obstacle to problem solving which arises from over-dependence on prior experiences

Other uses

*Real rigidity, and nominal rigidity, the resistance of prices and wages to marketchanges in macroeconomics *Ridgid, a brand of tools {{disambiguation