colour television tube

NOUN
22 LETTERS · STARTS WITH C

colour television tube is a valid 22-letter word worth 27 points in Scrabble and 35 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
C3O1L1O1U1R1T1E1L1E1V4I1S1I1O1N1T1U1B3E1
3 + 1 + 1 + 1 + 1 + 1 + 0 + 1 + 1 + 1 + 1 + 4 + 1 + 1 + 1 + 1 + 1 + 0 + 1 + 1 + 3 + 1 =27 PTS
DOUBLE WORD → 54TRIPLE WORD → 81
MEANING

What does colour television tube mean?