subsidiarity

NOUN /səb,sɪdɪ'æriti/
12 LETTERS · STARTS WITH S

subsidiarity is a valid 12-letter word worth 18 points in Scrabble and 19 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
S1U1B3S1I1D2I1A1R1I1T1Y4
1 + 1 + 3 + 1 + 1 + 2 + 1 + 1 + 1 + 1 + 1 + 4 =18 PTS
DOUBLE WORD → 36TRIPLE WORD → 54
MEANING

What does subsidiarity mean?