reversing thermometer

NOUN
21 LETTERS · STARTS WITH R

reversing thermometer is a valid 21-letter word worth 31 points in Scrabble and 35 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
R1E1V4E1R1S1I1N1G2T1H4E1R1M3O1M3E1T1E1R1
1 + 1 + 4 + 1 + 1 + 1 + 1 + 1 + 2 + 0 + 1 + 4 + 1 + 1 + 3 + 1 + 3 + 1 + 1 + 1 + 1 =31 PTS
DOUBLE WORD → 62TRIPLE WORD → 93
MEANING

What does reversing thermometer mean?

NOUN · 1 SENSE
1

A thermometer that registers the temperature in deep waters.