The medical section of the Merriam-Webster dictionary offers a search tool to enter anything from medical terms to abbreviations. It is constantly updated like the other sections of this dictionary.
You can find this dictionary here: https://www.merriam-webster.com/medical
Harvard Health Publishing’s Medical Dictionary of Health Terms is another monolingual dictionary where you can search alphabetically through a wide variety of medical terms.
It also includes a note for readers reminding them to take into account the date of the latest revision or update for all their content.
You can find the dictionary here: https://www.health.harvard.edu/a-through-c
MedicinePlus is a medical encyclopaedia that includes more than 4,000 articles on diseases, medical tests, symptoms, injuries and surgeries. In addition, it contains an archive of photos and illustrations referring to medical terms and situations.
You can find this dictionary here: https://medlineplus.gov/encyclopedia.html