ˈelə̇nˌvär noun
( -s )
Etymology: French élinvar, from él asticité invar iable invariable elasticity
: an alloy that contains about 50 percent iron, 36 percent nickel, and 12 percent chromium, that has low thermal expansivity and a modulus of elasticity virtually unaffected by changes in temperature, and that is used for springs for watches and other precise instruments