If you notice that your friends have been keeping their distance lately, they might be mad at you — or it could be your halitosis. Halitosis is a fancy way to say "bad breath."
A dentist or doctor is probably most likely to use the word halitosis, although it often comes up in mouthwash commercials too. The word itself comes from a merging of the Latin root halitus, or "breath," with the Greek suffix osis, "a state of disease." It's a condition with which you can actually be diagnosed, although it can usually be taken care of with a toothbrush and a tube of toothpaste.