IPA: /ˈspraɪt.fəl.nəs/
KK: /sprɪt̬fəl/
The quality of being lively, energetic, and full of spirit.
Her sprightfulness made the party much more enjoyable for everyone.
Sprightfulness is formed from "spright" (from Middle English "spryght", meaning spirit or lively) and "-fulness" (meaning the state of being full of). The word describes the state of being full of spirit or liveliness.
Think of 'spirit' when you hear 'spright' — it helps you remember that 'sprightfulness' means being full of liveliness.