9 letters · 11 points in Scrabble
adjective expletives used informally as intensifiers
originEtymology tree English darned Proto-Indo-European *-yōs Proto-Indo-European *-tHós Proto-Indo-European *-istHos Proto-Germanic *-istaz Proto-West Germanic *-ist Old English -est Middle English -est English -est English darnedest From darned + -est.
Etymology from Wiktionary, CC BY-SA 3.0