cumulation

NOUN /,kjumjə'leɪʃən/
10 LETTERS · 4 SYLLABLES · STARTS WITH C

cumulation is a valid 10-letter word worth 14 points in Scrabble and 20 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
C3U1M3U1L1A1T1I1O1N1
3 + 1 + 3 + 1 + 1 + 1 + 1 + 1 + 1 + 1 =14 PTS
DOUBLE WORD → 28TRIPLE WORD → 42
MEANING

What does cumulation mean?