a chemical element found in seawater and certain seaweeds, used in solution as an antiseptic; iodine is used by the thyroid gland (a large gland at the front of the neck, secreting a hormone that regulates the body's growth and development) to help regulate metabolism, and a shortage of iodine cancausegoiter (enlargement of the thyroid gland). —Clear Body, ClearMind: The Effective Purification Program