A right A<unk>  is a substance that has been engineered to interact with biological systems for a medical purpose, either a therapeutic (treat, augment, repair, or replace a tissue function of the body) or a diagnostic one. As a science,<unk> s is about fifty years old. The study of<unk> s is called<unk> s science or<unk> s engineering. It has experienced steady and strong growth over its history, with many companies investing large amounts of money into the development of new products.<unk> s science encompasses elements of medicine, biology, chemistry, tissue engineering and materials science. Note that a<unk>  is different from a biological material, such as bone, that is produced by a biological system. Additionally, care should be exercised in defining a<unk>  as biocompatible, since it is application-specific. A<unk>  that is biocompatible or suitable for one application may not be biocompatible in another.
Biomaterial
Biological agent
Biopharmaceutical
Cathartic
Inhalant
Chemical substance
Toxicant
Nutrient