: the quality of being strong and not easily broken, torn, etc.
This combination of strength and ductility makes spider silk extremely tough, matching the toughness of state-of-the-art carbon fibers such as Kevlar.MIT Technology Review
also: the quality of being difficult to cut or chew
… the extreme toughness of the beef … , which rendered it quite unfit … for any human consumption. Charles Dickens
b
: physical or emotional strength that allows someone to endure strain or hardship
Henin-Hardenne's unshakable mental toughness—she says one of her great joys in life is staving off a break point in a tight match—makes her all the more formidable. L. Jon Wertheim
c
: the quality of being severe or uncompromising
the toughness of the new sentencing guidelines
his toughness as a negotiator
The Minnesota senator referenced the story during her campaign to showcase her toughness on crime. Summer Concepcion and Matt Shuham
Besides teaching us how to hit with pads [in football], [Sister] Paulinus instructed us in English, history, and the love of God, with a distinctive combination of toughness and good humor. Luke Timothy Johnson
d
: the quality of being difficult to accomplish, resolve, endure, or deal with
the toughness of life in prison
the toughness of these decisions
After an appearance on British television, he is almost giddy at the toughness of the questions he faced. A. O. Scott
Just spritz on some Dawn Power Dissolver, wait 15 to 30 minutes depending on the toughness of the job, wipe with a sponge, and rinse.Cook's Illustrated