diarthrosis

NOUN /,daɪɑr'θroʊsɪs/
11 LETTERS · 4 SYLLABLES · STARTS WITH D

diarthrosis is a valid 11-letter word worth 15 points in Scrabble and 14 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
D2I1A1R1T1H4R1O1S1I1S1
2 + 1 + 1 + 1 + 1 + 4 + 1 + 1 + 1 + 1 + 1 =15 PTS
DOUBLE WORD → 30TRIPLE WORD → 45
MEANING

What does diarthrosis mean?