Painless diffuse enlargement of the thyroid gland is known as?

The correct answer is goiter, which refers to a painless diffuse enlargement of the thyroid gland. A goiter can occur with or without the presence of thyroid dysfunction and is often characterized by the thyroid being uniformly enlarged. This condition can result from a variety of factors, including iodine deficiency, autoimmune diseases, and hormonal imbalances.

While Hashimoto's thyroiditis does involve thyroid enlargement, it is typically associated with autoimmune inflammation and is often accompanied by other symptoms such as hypothyroidism. Graves' disease is another form of autoimmune disorder that usually results in hyperthyroidism and may present with a goiter; however, it is more common for it to be accompanied by additional symptoms like exophthalmos or hypermetabolic signs. Thyroiditis generally refers to inflammation of the thyroid which may or may not cause enlargement and is often associated with pain or discomfort.

Thus, a detailed understanding emphasizes that goiter is the primary term for the painless and diffuse enlargement of the thyroid gland itself without implying any specific etiology or associated symptoms.