Sprightliness, n.
The quality or state of being sprightly; liveliness; life; briskness; vigor; activity; gayety; vivacity. In dreams, observe with what a sprightliness and alacrity does she [the soul] exert herself! Addison.
Shades of meaning
Fernald has no entry of its own for sprightliness; he lists it under pertness.
Where he writes about it:
Liveliness and sprightliness are pleasant and commendable; smartness is a limited and showy acuteness or shrewdness, usually with unfavorable suggestion; pertness and sauciness are these qualities overdone, and regardless of the respect due to superiors. — from pertness