Inelasticus

Inelasticus is a Latin-derived term used in scientific contexts to denote the property of being not elastic. In this sense, it is applied to materials, processes, and phenomena that do not readily return to their original form after a deforming force is removed, or in which not all energy is recovered as kinetic energy.

Etymology and usage: The word derives from in- meaning not and elasticus meaning elastic. In modern English-language science, the adjective inelastic is more common, while inelasticus appears primarily in Latin-language texts or as a formal label in Latinized scientific terminology.

In physics and engineering, inelasticity describes deformation that is not fully reversible, such as plastic deformation, or energy loss that accompanies a collision or dynamic process. In an inelastic collision, momentum is conserved but kinetic energy is not; part of it is transformed into heat, sound, or internal energy.

In materials science, inelastic behavior is associated with plasticity, hysteresis, and damping. Materials exhibit yield strength and permanent strain after unloading, and viscoelastic or damping phenomena cause time-dependent deformation and energy dissipation under stress.

Notes: The term does not denote a distinct scientific entity by itself but serves as a classification attribute across disciplines. It is related to, but distinct from, elasticity, plasticity, and inelastic collision. See also elasticity and plasticity.