As they learn more about a disease (or respond to public misconceptions), doctors and scientists may change the name of familiar, widespread conditions.

SEID

Also known as Chronic Fatigue Syndrome, the official name for this difficult to understand condition in which those afflicted experience long bouts of otherwise unexplainable tiredness is myalgic encephalomyelitis. According to the American Academy of Family Physicians, less than a third of medical schools even cover the disease, so in 2015, the Institute of Medicine convened a committee and released a report outlining plans to get the condition more study and attention, which includes renaming it Systemic Exertion Intolerance Disease (SEID).

Hansen’s disease

Leprosy is one of the most notorious diseases in the world, and one that has afflicted millions. It’s most famously characterized by scaly skin, respiratory problems, and a loss of body parts. Mother Teresa dedicated her life to helping those with the disease, and to help dispel myths about it. (For example, while in Asia those who have it have been traditionally banished to ghettos, it’s actually very hard to catch.) The name “leprosy” comes from lepra, Latin for “scaly.” In the late 19th century, Norwegian doctor Gerhard Hansen identified the bacteria responsible for leprosy, and soon after the condition was renamed after him.

ADHD

Kids who had trouble concentrating or sitting still were once dismissed as “hyperactive.” In the 18th century, the condition was identified by British doctor Alexander Crichton and titled “mental restlessness,” and was subsequently listed in the DSM-II psychological disorders manual as “hyperkinetic reaction of childhood,” leading to the colloquial term of “hyperactive.” When the DSM-III came out in 1980, the condition was renamed ADD or “attention deficit disorder.” Today’s its known as ADHD, for “attention deficit and hyperactive disorder,” so as to encompass a wider range of symptoms and conditions.