Educational Content: This article is for informational purposes only and does not constitute medical advice. Always consult a healthcare provider for diagnosis and treatment.

Definition of Thymus

Medically reviewed by Min Clinic Staff | Updated: January 2026

Thymus: An organ that is located in the upper chest behind the breastbone and in front of the lower neck in which the immune cells called T lymphocytes mature and multiply in early life. The thymus begins to shrink after puberty.