reflex response

NOUN
15 LETTERS · STARTS WITH R

reflex response is a valid 15-letter word worth 26 points in Scrabble and 29 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
R1E1F4L1E1X8R1E1S1P3O1N1S1E1
1 + 1 + 4 + 1 + 1 + 8 + 0 + 1 + 1 + 1 + 3 + 1 + 1 + 1 + 1 =26 PTS
DOUBLE WORD → 52TRIPLE WORD → 78
MEANING

What does reflex response mean?