ring armour

NOUN
11 LETTERS · STARTS WITH R

ring armour is a valid 11-letter word worth 13 points in Scrabble and 17 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
R1I1N1G2A1R1M3O1U1R1
1 + 1 + 1 + 2 + 0 + 1 + 1 + 3 + 1 + 1 + 1 =13 PTS
DOUBLE WORD → 26TRIPLE WORD → 39
MEANING

What does ring armour mean?