The word "thymus persiatens hyperplastica" is a medical term referring to an abnormal growth of the thymus gland. The spelling of this word can be difficult to understand, but the International Phonetic Alphabet (IPA) provides a useful guide. The first two syllables are pronounced as "thai-muhs," while the third syllable is pronounced as "puhr-shee-uh-tens." The final two syllables are pronounced as "hi-per-plas-ti-kuh." The spelling may seem intimidating, but it is important for medical professionals to be able to understand and use these terms correctly.
A thymus which, instead of atrophying, persists in the adolescent or adult, or even hypertrophies.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.