time derivative

15 LETTERS · STARTS WITH T

time derivative is a valid 15-letter word worth 23 points in Scrabble and 26 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS

T1I1M3E1D2E1R1I1V4A1T1I1V4E1

1 + 1 + 3 + 1 + 0 + 2 + 1 + 1 + 1 + 4 + 1 + 1 + 1 + 4 + 1 =23 PTS

DOUBLE WORD → 46TRIPLE WORD → 69

MEANING

What does time derivative mean?