BSE is a serious brain disease that hits cows. The long name is bovine spongiform encephalopathy: bovine means “of cows,” spongiform means “like a sponge” (the brain fills with tiny holes), and encephalopathy means a disease of the brain. Almost nobody says the long name in ordinary life. People say mad cow disease. In the 1980s and 1990s it became famous in Britain, because sick cows were in the food chain, and a few people later got a related brain disease. You say the letters B-S-E. It is a formal, scientific label; the everyday English is much more informal and a bit blunt.