l 1 i 1 g 2 h 4 t 1 h 4 e 1 a 1 r 1 t 1 e 1 d 2 n 1 e 1 s 1 s 1
16 letters · 24 points in Scrabble
Meaning
noun the cheerful feeling you have when nothing is troubling you
originFrom lighthearted (adjective) (any sense) + -ness (suffix forming nouns).
Etymology from Wiktionary, CC BY-SA 3.0