Synonyms and related words :
backbone, bottom, chutzpah, decisiveness, endurance, energy, force, fortitude, grit, guts, gutsiness, guttiness, hardiness, heart, heart of oak, heartiness, lustihood, lustiness, mettle, might, mightiness, moxie, nerve, obstinacy, pith, pluck, potency, power, powerfulness, robustness, ruggedness, sand, spirit, spunk, stalwartness, stamina, staying power, sticking power, stout heart, stoutness, strength, strength of will, sturdiness, toughness, vigor, vigorousness, vitality