You can make 178 valid words from the letters in DEFFIRSU using the Scrabble US/CAN dictionary.
How many points is DEFFIRSU worth in Scrabble?
DEFFIRSU is worth 15 points in Scrabble (US/CAN) and 16 points in Words With Friends.
How do I use the Word Unscrambler tool?
Enter any letters into the input box and press Search. The tool will return every valid English word that can be made from those letters using the dictionary you select.