Same word as verve:

activity, ardor, dash, drive, endurance, fire, force, forcefulness, get-up-and-go, go, gumption, gusto, hardihood, intensity, juice, liveliness, moxie, passion, pep, pizzazz, pluck, power, punch, sparkle, spirit, spunk, stamina, steam, strength, toughness, vigor, vim, virility, vitality, zeal, zest, zing, zip, �lan