ne'er-do-well

NOUN /nɜrdu,wel/
13 LETTERS · STARTS WITH N

ne'er-do-well is a valid 13-letter word worth 14 points in Scrabble and 17 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
N1E1'0E1R1-0D2O1-0W4E1L1L1
1 + 1 + 0 + 1 + 1 + 0 + 2 + 1 + 0 + 4 + 1 + 1 + 1 =14 PTS
DOUBLE WORD → 28TRIPLE WORD → 42
MEANING

What does ne'er-do-well mean?