Tough

1. superl. Severe; violent; as, a tough storm.
2. superl. Having the quality of flexibility without brittleness; yielding to force without breaking; capable of resisting great strain; as, the ligaments of animals are remarkably tough.
3. superl. Not easily broken; able to endure hardship; firm; strong; as, tough sinews.
4. superl. Not easily separated; viscous; clammy; tenacious; as, tough phlegm.
5. superl. Stiff; rigid; not flexible; stubborn; as, a tough bow.

The word meanings were obtained from OPTED(The Online Plain Text English Dictionary), which is based on “The Project Gutenberg Etext of Webster’s Unabridged Dictionary” which is in turn based on the 1913 US Webster’s Unabridged Dictionary (See Project Gutenburg), as a text file.