monetary unit

NOUN /mɑnɪ,tɛri_'junɪt/
13 LETTERS · 5 SYLLABLES · STARTS WITH M

monetary unit is a valid 13-letter word worth 17 points in Scrabble and 20 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
M3O1N1E1T1A1R1Y4U1N1I1T1
3 + 1 + 1 + 1 + 1 + 1 + 1 + 4 + 0 + 1 + 1 + 1 + 1 =17 PTS
DOUBLE WORD → 34TRIPLE WORD → 51
MEANING

What does monetary unit mean?