Engineering definitions

Strength

A material's ability to resist applied forces without permanently changing shape or breaking in any way

Ductility

A material's ability to be stretched or reshaped under a tensile force without losing strength

Malleability

A material's ability to be bent or reshaped under a compressive force

Hardness

A material's ability to withstand force without deformation, scratching, penetration, and indentation.

Toughness

the ability of a material to resist fracture

Brittleness

The tendency to crack or break

Stiffness

A material's ability to hold its shape without bending