When talking about disease, the term "most transmittable" refers to the ease with which a virus or bacteria can be spread from one person to another. Antonyms for this term might include "least transmittable," which would refer to a disease that is difficult to spread, or "moderately transmittable," indicating that the disease is neither highly contagious nor difficult to contract. Other antonyms might include terms like "impervious," "resistant," or "uncommunicable," all of which describe diseases that are not easily transmitted from person to person. Regardless of which antonym is used, it is important to remember that some diseases are highly contagious and can spread quickly, while others are much less so, and may only be contracted under special circumstances or through direct contact with an infected person.