defect of speech

NOUN
16 LETTERS · STARTS WITH D

defect of speech is a valid 16-letter word worth 30 points in Scrabble and 32 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
D2E1F4E1C3T1O1F4S1P3E1E1C3H4
2 + 1 + 4 + 1 + 3 + 1 + 0 + 1 + 4 + 0 + 1 + 3 + 1 + 1 + 3 + 4 =30 PTS
DOUBLE WORD → 60TRIPLE WORD → 90
MEANING

What does defect of speech mean?