These words refer to what is healthful, clean, germ-free or germ-destroying. Sanitary , the most informal of these, pertains mostly to what preserves or is favourable to health, particularly by virtue of its cleanliness. But since it has a quasi-medical tone and suggests a degree of cleanliness quite beyond that of the word clean, it can also imply a germ-free condition: A common drinking cup may be clean without being sanitary . Hygienic is much broader in scope than sanitary ; in referring to things preserving or promoting health, it can refer more readily than sanitary to other aspects of healthfulness than those pertaining to cleanliness or freedom from germs: Sleeping with windows is hygienic . But it can refer generally to freedom from germs where the additional implications of extreme cleanliness in sanitary would be inappropriate: It is not hygienic to have a well situated on lower ground than a septic tank.

The remaining words relate exclusively to the absence or destruction of germs causing disease or infection. Sterile refers particularly to things made free of germs: sterile bandages; using only sterile instruments during the operation; precautions to make sure the wound remained sterile . Aseptic refers especially to the absence of germs from living tissue, or to the absence of putrefactive infection; in this, it is restricted to one aspect of sterile , with a gain in precision. This lack of infection may be fortuitous rather than induced: a cut that had luckily remained aseptic ; using sterile instruments so that the incision would be aseptic . Antiseptic can also refer to something kept sterile against germs or infection, including living tissue, though it applies to other things as well. In its particular area of relevance, it points to the counteracting of infections by the actual destruction of germs that may already be present: an antiseptic solution of sodium perborate.