What does ductile mean?
Ductility
a measure of a material's ability to undergo significant plastic deformation before rupture, which may be expressed as percent elongation or percent area reduction from a tensile test
Ductility is a measure of a material's ability to undergo significant plastic deformation before rupture, which may be expressed as percent elongation or percent area reduction from a tensile test.  According to Shigley's Mechanical Engineering Design (10th Ed.) [1] significant denotes about 5.0 percent elongation (Section 5.3, p. 233). See also Eq. 2–12, p. 50 for definitions of percent elongation and percent area reduction. Ductility is often characterized by a material's ability to be stretched into a wire.  