Goiter: A noncancerous enlargement of the thyroid gland. With a goiter, the levels of thyroid hormones may be normal (euthyroid), elevated (hyperthyroidism), or decreased (hypothyroidism). Goiter is an enlargement of the thyroid gland, which is situated across the front of the neck just below the Adam’s apple {larynx}. The swelling of the gland may be so great as almost to […]