subphylum urochordata

NOUN
21 LETTERS · STARTS WITH S

subphylum urochordata is a valid 21-letter word worth 38 points in Scrabble and 43 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
S1U1B3P3H4Y4L1U1M3U1R1O1C3H4O1R1D2A1T1A1
1 + 1 + 3 + 3 + 4 + 4 + 1 + 1 + 3 + 0 + 1 + 1 + 1 + 3 + 4 + 1 + 1 + 2 + 1 + 1 + 1 =38 PTS
DOUBLE WORD → 76TRIPLE WORD → 114
MEANING

What does subphylum urochordata mean?