nervous disorder

NOUN /nɜrvəs_dɪs'ɔrdər/
16 LETTERS · STARTS WITH N

nervous disorder is a valid 16-letter word worth 20 points in Scrabble and 23 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
N1E1R1V4O1U1S1D2I1S1O1R1D2E1R1
1 + 1 + 1 + 4 + 1 + 1 + 1 + 0 + 2 + 1 + 1 + 1 + 1 + 2 + 1 + 1 =20 PTS
DOUBLE WORD → 40TRIPLE WORD → 60
MEANING

What does nervous disorder mean?