Appendicitis is the illness in which your appendix — that small extra tube on the large intestine — swells and hurts. The pain often starts near the middle of the belly and later settles in the lower right side; a person may also feel sick or feverish. Doctors treat it as urgent, because if the tube bursts the infection can spread. The word is straight medical naming: the part plus an ending that means “this is swollen and angry.” You will hear it from doctors and in hospital stories. One messy truth for learners in Taiwan: at home almost everyone says 盲腸炎, as if the whole blind gut were the problem. The English word is more precise. It names trouble in the appendix, not in the whole neighbouring pouch.