substernal definition
U.S. National Library of Medicine(0.00 / 0 votes)Rate this definition: Goiter, Substernal. An enlarged THYROID GLAND with at least 50% of the gland situated behind the STERNUM. It is an unusual presentation of an intrathoracic goiter. Substernal goiters frequently cause compression on the TRACHEA leading to deviation, narrowing, and respiratory symptoms.