%stamina%

n. pl. 1. The fixed, firm part of a body, which supports it or gives it strength and solidity; as, the bones are the stamina of animal bodies; the ligneous parts of trees are the stamina which constitute their strength. [ 1913 Webster ]

2. Whatever constitutes the principal strength or support of anything; backbone; vigor; as, the stamina of a constitution or of life; the stamina of a State. [ 1913 Webster ]

He succeeded to great captains who had sapped the whole stamina and resistance of the contest. De Quincey. [ 1913 Webster ]

3. Hence: The power of endurance; the ability to withstand fatigue, disease, deprivation, etc., and continue working. [ 1913 Webster +PJC ]