Source : Webster's Revised Unabridged Dictionary (1913)

Sinewy \Sin"ew*y\, a.
   1. Pertaining to, consisting of, or resembling, a sinew or
      sinews.

            The sinewy thread my brain lets fall. --Donne.

   2. Well braced with, or as if with, sinews; nervous;
      vigorous; strong; firm; tough; as, the sinewy Ajax.

            A man whose words . . . were so close and sinewy.
                                                  --Hare.

Source : WordNet®

sinewy
     adj 1: (of meat) full of sinews; especially impossible to chew
            [syn: {fibrous}, {stringy}, {unchewable}]
     2: consisting of tendons or resembling a tendon [syn: {tendinous}]
     3: (of a person) possessing physical strength and weight;
        rugged and powerful; "a hefty athlete"; "a muscular
        boxer"; "powerful arms" [syn: {brawny}, {hefty}, {muscular},
         {powerful}]