defective verb

14 LETTERS · STARTS WITH D

defective verb is a valid 14-letter word worth 27 points in Scrabble and 31 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS

D2E1F4E1C3T1I1V4E1V4E1R1B3

2 + 1 + 4 + 1 + 3 + 1 + 1 + 4 + 1 + 0 + 4 + 1 + 1 + 3 =27 PTS

DOUBLE WORD → 54TRIPLE WORD → 81

MEANING

What does defective verb mean?