Which condition is characterized by the enlargement of the thyroid gland?

The condition characterized by the enlargement of the thyroid gland is goiter. A goiter reflects the increase in size of the thyroid gland and can occur due to various factors, including iodine deficiency, autoimmune diseases like Graves' disease or Hashimoto's thyroiditis, and certain nodular conditions. When the thyroid enlarges, it may produce excess hormones or lead to imbalances that can cause symptoms of thyroid dysfunction, but the core defining feature is the enlargement itself.

In contrast, hyperthyroidism is a condition stemming from excessive thyroid hormone production, which may or may not involve enlargement of the gland. Hypothyroidism refers to an underactive thyroid that produces insufficient hormones. A chalazion, on the other hand, involves a blockage in a sebaceous gland of the eyelid and is unrelated to the thyroid gland. Thus, goiter is specifically recognized for its defining characteristic of thyroid enlargement.