The quality of being darling; the state of being beloved, cherished, or affectionately charming.
From 'darling' + the '-ness' suffix, creating an abstract noun. 'Darling' comes from Old English 'deorling' (little dear), so 'darlingness' is the quality of that endearment.
While 'darlingness' is grammatically valid, we almost never use it—we just say 'She's such a darling!' instead, showing how abstract nouns for emotional qualities feel over-constructed in modern English.
Complete word intelligence in one call. Free tier — 50 lookups/day.