degenerative disorder

NOUN
21 LETTERS · STARTS WITH D

degenerative disorder is a valid 21-letter word worth 27 points in Scrabble and 30 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
D2E1G2E1N1E1R1A1T1I1V4E1D2I1S1O1R1D2E1R1
2 + 1 + 2 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 4 + 1 + 0 + 2 + 1 + 1 + 1 + 1 + 2 + 1 + 1 =27 PTS
DOUBLE WORD → 54TRIPLE WORD → 81
MEANING

What does degenerative disorder mean?