Synonyms and related words :
acceleration, activity, animation, ardor, brio, briskness, catalyst, clout, compulsion, drive, driving force, elan, encouragement, energy, enthusiasm, getaway, glow, goad, gusto, impellent, impelling force, impetuosity, impulse, impulsion, incentive, incitation, incitement, inspiration, irresistible force, joie de vivre, life, liveliness, lustiness, mettle, moment, momentum, motivation, motive power, perkiness, pertness, pickup, power, propulsion, push, quickening, robustness, speedup, spirit, spiritedness, spur, step-up, stimulant, stimulation, stimulus, thrust, vivacity, warmth, zest, zestfulness