Vivacious, a.
Etymology: [L. vívax, -acis, fr. vivere to live. See Vivid.]
1. Having vigorous powers of life; tenacious of life; long-lived. [Obs.] Hitherto the English bishops have been vivacious almost to wonder. . . . But five died for the first twenty years of her [Queen Elizabeth's] reign. Fuller. The faith of Christianity is far more vivacious than any mere ravishment of the imagination can ever be. I. Taylor.
2. Sprightly in temper or conduct; lively; merry; as, a vivacious poet. "Vivacious nonsense." V. Knox.
3. (Bot.)
Living through the winter, or from year to year; perennial. [R.]
1 more senses
Syn. -- Sprightly; active; animated; sportive; gay; merry; jocund; light- hearted. -- Vi*va"cious*ly, adv. -- Vi*va"cious*ness, n.
Shades of meaning
Fernald has no entry of its own for vivacious; he lists it under alive.
He lists it without comment; the entries above explain its neighbors.