Thyreoncus is a medical term that refers to a tumor of the thymus gland, which is an organ in the chest that plays a role in the immune system. The spelling of thyreoncus is based on its Greek origin, which uses the letter theta (θ) instead of the letter "th". In the International Phonetic Alphabet (IPA), thyreoncus is pronounced as /θaɪˈrɒŋkəs/, with the emphasis on the second syllable. Understanding the phonetic transcription can help with pronouncing and spelling difficult medical terms.
Goiter, struma, thyreocele.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.