inelastiline

Inelastiline is an Estonian adjective meaning unable to return to its original shape or size after a deforming force is removed. It contrasts with elastne (the Estonian word for elastic) and with elastsus (elasticity), which describe materials or systems that recover their initial form. The term also covers processes that are irreversible or dissipative.

In physics, an inelastic collision is described in Estonian as "inelastiline põrkumine." It is a collision in which kinetic energy is not conserved; part of the energy is transformed into heat, sound, or internal energy of the bodies. In closed systems, total energy and momentum are conserved, but the kinetic energy before and after the collision differs.

In materials science, inelastic deformation describes permanent, plastically irreversible changes in shape after the stress is removed. Such behavior is typical of metals, polymers and many other materials when yielding occurs. Some materials exhibit viscoelastic or rate-dependent inelastic responses, where deformation depends on time and loading rate.

In economics, inelastic demand (inelastiline nõudlus) refers to a situation where quantity demanded changes little in response to price changes; the price elasticity of demand is less than one in absolute value. This concept helps explain demand for essential goods or goods with few substitutes. Inelastic supply is defined similarly with respect to price changes.

Etymology and usage: The word derives from Latin inelasticus, with in- meaning "not" and elasticus meaning "elastic." In Estonian scientific and technical texts, inelastiline is the standard form; the term is used across disciplines as an adjective and in compounds.