The state or quality of being delighted; the condition of experiencing great pleasure or joy.
From delighted (past participle of delight) plus the abstract noun suffix -ness, creating a noun that describes the emotional state of being delighted.
Adding -ness to an already-suffixed adjective (delighted + ness) creates what linguists call 'stacked suffixes,' and while it's grammatically correct, it sounds awkward—which is why we rarely use this word and prefer simply saying 'delight' or 'happiness' instead.
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