| Noun | 1. | hyperpituitarism - excessive activity of the pituitary gland (especially overactivity of the anterior lobe which leads to excess secretion of growth hormone)acromegalia, acromegaly - enlargement of bones of hands and feet and face; often accompanied by headache and muscle pain and emotional disturbances; caused by overproduction of growth hormone by the anterior pituitary gland (due to a tumor) | |