bipolar disorder

NOUN
16 LETTERS · STARTS WITH B

bipolar disorder is a valid 16-letter word worth 21 points in Scrabble and 24 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
B3I1P3O1L1A1R1D2I1S1O1R1D2E1R1
3 + 1 + 3 + 1 + 1 + 1 + 1 + 0 + 2 + 1 + 1 + 1 + 1 + 2 + 1 + 1 =21 PTS
DOUBLE WORD → 42TRIPLE WORD → 63
MEANING

What does bipolar disorder mean?