Khellin is not typically defined in a medical dictionary as it is not a medical term itself, but rather a chemical compound found in certain plants. However, Khellin is known for its use in traditional medicine and has been studied in modern medicine for its potential therapeutic effects. Here's the definition of Khellin from a chemistry perspective:

Khellin (C10H8O3) is a chemical compound derived from the seeds of the plant Ammi visnaga, also known as khella or Bishop's weed. It belongs to the class of organic compounds called furanocoumarins, which are naturally occurring aromatic organic compounds containing a furan ring (a five-membered aromatic heterocycle with four carbon atoms and one oxygen atom) fused to a coumarin ring (a benzene ring fused to α-pyrone).

Khellin has been used in traditional medicine for treating various conditions, including asthma, angina pectoris, and headaches. Modern research has investigated its potential as a therapeutic agent for cardiovascular diseases, cancer, and other medical conditions. However, more studies are needed to establish its safety and efficacy before it can be widely used in modern medicine.

I am not aware of a widely recognized medical definition for the term "Ammi." It is possible that it could refer to a specific medical condition, treatment, or concept in a certain regional or cultural context. However, without more information, I cannot provide an accurate medical definition for this term.

In botanical terms, "Ammi" refers to a genus of plants in the family Apiaceae, also known as the carrot or parsley family. Some species of Ammi are used in traditional medicine, but there is limited scientific evidence supporting their effectiveness for specific medical conditions. It's important to consult with a healthcare professional before using any herbal remedies or supplements.