Three-day measles is also known as rubella, German measles, and light measles. These synonyms are used interchangeably to refer to a contagious viral infection caused by the rubella virus. Rubella typically causes mild symptoms in children and adults, including a rash that lasts for three days, low fever, and swollen lymph nodes. However, the infection can be dangerous for pregnant women as it can cause severe birth defects in the fetus. Rubella vaccination is widely available, and a single vaccination can provide lifelong immunity against the virus. By using the synonyms to refer to the infection, it becomes easier for individuals to understand and recognize the symptoms and take the necessary precautions to prevent the spread of the virus.