TOUGH, adjective tuf.
1. Having the quality of flexibility without brittleness; yielding to force without breaking. The ligaments of animals and of India rubber are remarkably toughtough timber, like young ash, is the most proper for the shafts and springs of a carriage.
2. Firm; strong; not easily broken; able to endure hardship; as an animal of a tough frame.
3. Not easily separated; viscous; clammy; tenacious; ropy; as tough phlegm.
4. Stiff; not flexible.