Source : Webster's Revised Unabridged Dictionary (1913)

Tough \Tough\, a. [Compar. {Tougher}; superl. {Toughest}.] [OE.
   tough, AS. t[=o]h, akin to D. taai, LG. taa, tage, tau, OHG.
   z[=a]hi, G. z[aum]he, and also to AS. getenge near to, close
   to, oppressive, OS. bitengi.]
   1. 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. ``Tough roots and stubs. '' --Milton.

   2. Not easily broken; able to endure hardship; firm; strong;
      as, tough sinews. --Cowper.

            A body made of brass, the crone demands, . . . Tough
            to the last, and with no toil to tire. --Dryden.

            The basis of his character was caution combined with
            tough tenacity of purpose.            --J. A.
                                                  Symonds.

   3. Not easily separated; viscous; clammy; tenacious; as,
      tough phlegm.

   4. Stiff; rigid; not flexible; stubborn; as, a tough bow.

            So tough a frame she could not bend.  --Dryden.

   5. Severe; violent; as, a tough storm. [Colloq.] `` A tough
      debate. '' --Fuller.

   {To make it tough}, to make it a matter of difficulty; to
      make it a hard matter. [Obs.] --Chaucer.

Source : WordNet®

tough
     n 1: someone who learned to fight in the streets rather than
          being formally trained in the sport of boxing [syn: {street
          fighter}]
     2: an aggressive and violent young criminal [syn: {hood}, {hoodlum},
         {goon}, {punk}, {thug}, {toughie}, {strong-armer}]
     3: a cruel and brutal fellow [syn: {bully}, {hooligan}, {ruffian},
         {roughneck}, {rowdy}, {yob}, {yobo}, {yobbo}]

tough
     adj 1: not given to gentleness or sentimentality; "a tough
            character" [ant: {tender}]
     2: very difficult; severely testing stamina or resolution; "a
        rugged competitive examination"; "the rugged conditions of
        frontier life"; "the competition was tough"; "it's a tough
        life"; "it was a tough job" [syn: {rugged}]
     3: physically toughened; "the tough bottoms of his feet" [syn:
        {toughened}] [ant: {tender}]
     4: substantially made or constructed; "sturdy steel shelves";
        "sturdy canvas"; "a tough all-weather fabric"; "some
        plastics are as tough as metal" [syn: {sturdy}]
     5: violent and lawless; "the more ruffianly element"; "tough
        street gangs" [syn: {ruffianly}]
     6: feeling physical discomfort or pain (`tough' is occasionally
        used colloquially for `bad'); "my throat feels bad"; "she
        felt bad all over"; "he was feeling tough after a restless
        night" [syn: {bad}]
     7: tough to cut or chew [ant: {tender}]
     8: unfortunate or hard to bear; "had hard luck"; "a tough
        break" [syn: {hard}]