sideward motion

15 LETTERS · STARTS WITH S

sideward motion is a valid 15-letter word worth 21 points in Scrabble and 23 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS

S1I1D2E1W4A1R1D2M3O1T1I1O1N1

1 + 1 + 2 + 1 + 4 + 1 + 1 + 2 + 0 + 3 + 1 + 1 + 1 + 1 + 1 =21 PTS

DOUBLE WORD → 42TRIPLE WORD → 63

MEANING

What does sideward motion mean?