A Dictionary of the Book of Mormon/Irreantum
IRREANTUM. The name given by Lehi's colony to an arm of the Indian Ocean, on the eastern coast of Arabia. On its shore Nephi and his brethren built the ship that carried them to this continent. It was either the Persian Gulf or Gulf of Oman, the which does not clearly appear from the records. Nephi informs us that the meaning of the word Irreantum is many waters.