n. a form of hypothyroidism, mostly found in children, whereby the thyroid gland has failed to develop normally. Affected children either have no thyroid gland or one that is very small. Where the thyroid should be is a mass of fibrous tissue. Also known as athyreotic cretinism. See also cretinism.
ATHYREOSIS: "A person with athyreosis has either no thyroid gland or one that has not developed in the expected manner."