dumbfound

VERB /dəm'fæʊnd/
9 LETTERS · 2 SYLLABLES · STARTS WITH D

dumbfound is a valid 9-letter word worth 18 points in Scrabble and 23 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
D2U1M3B3F4O1U1N1D2
2 + 1 + 3 + 3 + 4 + 1 + 1 + 1 + 2 =18 PTS
DOUBLE WORD → 36TRIPLE WORD → 54
MEANING

What does dumbfound mean?