toughness

/ˈtəf-nəs/

+ -ness

noun

  1. the quality or state of being tough: such as

  2. the quality of being strong and not easily broken, torn, etc.; also : the quality of being difficult to cut or chew

  3. physical or emotional strength that allows someone to endure strain or hardship

This combination of strength and ductility makes spider silk extremely tough, matching the toughness of state-of-the-art carbon fibers such as Kevlar.