Paediatrics is the area of medicine that looks after children and their illnesses. In English this word looks plural, with an s, but we treat it as one field: “Paediatrics is hard work,” not “are”. It covers babies, children, and often teenagers, until adult doctors take over. British spelling paediatrics; American pediatrics. Though actually, on a hospital sign you may only see paediatric, the adjective, as in paediatric department — that department is still paediatrics. Everyday English also just says children’s medicine.