vigorous

adj. robust, strong; energetic, active

Adjective
1. characterized by forceful and energetic action or activity; "a vigorous hiker"; "gave her skirt a vigorous shake"; "a vigorous campaign"; "a vigorous foreign policy"; "vigorous opposition to the war"
(similar) energetic
2. strong and active physically or mentally; "a vigorous old man who spent half of his day on horseback"- W.H.Hudson
(similar) robust

(a.)
Possessing vigor; full of physical or mental strength or active force; strong; lusty; robust; as, a vigorous youth; a vigorous plant.
  

(a.)
Exhibiting strength, either of body or mind; powerful; strong; forcible; energetic; as, vigorous exertions; a vigorous prosecution of a war.
  

lao3 dang1 yi4 zhuang4
Old but more spirited.
Said of a person that is vigorous in spirit though clearly of old age. Compare with 老骥伏枥 (lao3 ji4 fu2 li4).

fan3 lao3 huan2 tong2
Recovering the youthful vigour.
(No further explanation)

Synonyms and related words:
ablaze, acid, active, acute, afire, aggressive, animated, ardent, armipotent, athletic, authoritative, balmy, beefy, biting, blooming, blossoming, boiling over, booming, bouncing, breathless, brisk, burning, cartilaginous, chewy, clear, cogent, cohesive, cordial, coriaceous, corrosive, cutting, dashing, delirious, doughty, driving, drunk, durable, dynamic, effective, energetic, enterprising, enthusiastic, excited, exuberant, fair, fat, febrile, fervent, fervid, fevered, feverish, fibrous, fiery, fit, flaming, flourishing, flowering, flush, flushed, forceful, forcible, forcy, fruiting, full of beans, full of pep, full-blooded, full-strength, glowing, go-go, going strong, gristly, gutsy, gutty, halcyon, hale, hale and hearty, hard, hard as nails, hard-hitting, hardy, healthy, hearty, heated, hefty, high-potency, high-powered, high-pressure, high-tension, hot, husky, impassioned, imperative, impetuous, impressive, in force, in full swing, in good case, in power, incisive, intense, intoxicated, iron-hard, irresistible, keen, kinetic, lasting, leatherlike, leathery, lively, living, lusty, masterful, mettlesome, mighty, mighty in battle, mordant, muscular, nervous, nervy, obstinate, on fire, operative, palmy, passionate, penetrating, peppy, piercing, piping, poignant, potent, powerful, prepotent, prospering, proud, puissant, punchy, red-blooded, red-hot, resilient, resistant, robust, robustious, robustuous, ropy, rosy, rough-and-ready, rude, rugged, ruling, sensational, sinewed, sinewy, slashing, sleek, smacking, snappy, spanking, spirited, sprightly, spry, stalwart, steaming, steamy, steely, stiff, stout, strapping, strenuous, striking, stringy, strong, strong as brandy, strong as strong, strong-willed, stubborn, sturdy, take-charge, take-over, telling, tenacious, thriving, tough, tough as leather, trenchant, unrestrained, untiring, valid, vibrant, vigil, viscid, vital, vivacious, vivid, warm, wiry, zealous, zestful, zesty, zippy