ˈīˌzäd-, ˈīzəd- noun
Usage: usually capitalized I
Etymology: after E. G. Izod, 20th century English mechanical engineer
: a test of a metal's or plastic's resistance to impact that is made by determining the amount of energy in foot-pounds needed by a swinging hammer to fracture a notched test piece of the material held in a vertical position and supported at its lower end