rapidity

NOUN /rə'pɪdɪti/
8 LETTERS · 4 SYLLABLES · STARTS WITH R

rapidity is a valid 8-letter word worth 14 points in Scrabble and 14 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
R1A1P3I1D2I1T1Y4
1 + 1 + 3 + 1 + 2 + 1 + 1 + 4 =14 PTS
DOUBLE WORD → 28TRIPLE WORD → 42
MEANING

What does rapidity mean?