fibrous joint

NOUN
13 LETTERS · STARTS WITH F

fibrous joint is a valid 13-letter word worth 24 points in Scrabble and 29 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
F4I1B3R1O1U1S1J8O1I1N1T1
4 + 1 + 3 + 1 + 1 + 1 + 1 + 0 + 8 + 1 + 1 + 1 + 1 =24 PTS
DOUBLE WORD → 48TRIPLE WORD → 72
MEANING

What does fibrous joint mean?