If something is hygienic it is good for your health or promotes healthy habits. Mothers are always spouting hygienic messages like "Wash your hands!" or "Brush your teeth!"
Hygienic comes from the ancient Greek word hygies, meaning "healthy" or, literally, "living well." This state was represented by the Goddess Hygieia, the embodiment of health and cleanliness. Hygienic is often used indiscriminately with sanitary, though in fact sanitary implies a particular nose-wrinkling emphasis on proper sewage disposal and clean water that is only a part of the Greeks' original concept of a more comprehensive physical and mental well being.