rue·ful 
/ˈru:fəl/ adjective
/ˈru:fəl/ adjective : showing or feeling regret for something done
▪ He gave me a rueful smile and apologized.
▪ He gave me a rueful smile and apologized.
— rue·ful·ly adverb
▪ “I still have a scar from the accident,” he said ruefully.
▪ “I still have a scar from the accident,” he said ruefully.
