propeller plane

NOUN /prə'pɛlər_pleɪn/
15 LETTERS · STARTS WITH P

propeller plane is a valid 15-letter word worth 20 points in Scrabble and 27 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
P3R1O1P3E1L1L1E1R1P3L1A1N1E1
3 + 1 + 1 + 3 + 1 + 1 + 1 + 1 + 1 + 0 + 3 + 1 + 1 + 1 + 1 =20 PTS
DOUBLE WORD → 40TRIPLE WORD → 60
MEANING

What does propeller plane mean?