acromegaly. abnormal enlargement of the extremities of the skeleton due to overgrowth of connective tissue and increased appositional growth of bone caused by hypersecretion of growth hormone (GH) from the pituitary gland in adults. (Marie's disease), a condition caused by hyperfunction of the pituitary gland in adults. Characterized by enlargement of the skeletal extremities, including the feet, hands, mandible, and nose. Acromegaly.