Emily Dickinson Lexicon

TOUGH, a. [tuf; Sax. toh; D. taai; G. zähe. Qu. tight, thick.]

1. Having the quality of flexibility without brittleness; yielding to force without breaking. The ligaments of animals and India rubber are remarkably tough. Tough 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. Dryden.
3. Not easily separated; viscous; clammy; tenacious; ropy; as, tough phlegm.
4. Stiff; not flexible.