Large, Triangular-Shaped Yacht Sail
Puzzle 11 of Elvis Presley Easy Pack
Question is: Large, Triangular-Shaped Yacht Sail
and the answer is: SPINNAKER
Word Meaning:
SPINNAKER — (nautical, sailing) A sail supplemental to the mainsail, especially a triangular one, used on yachts for running before the wind.
Definitions from Wiktionary.