What is the term used to describe the ability of a material to deform under stress without breaking?

The term that describes the ability of a material to deform under stress without breaking is ductility. Ductility refers to the capacity of a material to undergo significant plastic deformation before rupture or failure. This property is crucial in manufacturing processes where materials may be bent, stretched, or shaped, allowing them to absorb energy and accommodate changes in form without losing structural integrity.

In contrast, toughness relates to a material's ability to absorb energy and plastically deform without fracturing, but it encompasses both ductility and strength. Elasticity refers to a material's ability to return to its original shape after the stress is removed, which does not imply permanent deformation. Hardness measures a material's resistance to localized plastic deformation, often assessed through indentation or scratching tests, and does not directly relate to overall deformability under stress.