sinew
I
noun
brawn, brawniness, effectiveness, endurance, energy, force, forcefulness, grit, lustiness, might, muscle, nervus, potence, potency, power, powerfulness, robustness, stamina, staying power, strength, thews, vigor, vigorousness
II
index
prowess (bravery)
Burton's Legal Thesaurus.
William C. Burton.
2006