The term biomaterial refers to several different types of material. It is used to refer to biological matter, biocompatible material, biologically derived material, and bio-based material. Biologically derived material, also called biotic material, is natural material from living tissues. This includes wood, chitin, crude oil, and some organic compounds found in the soil. Biotic material is termed biomass when the living-source has little importance to the final product, as in the case of biofuels.

After processing, biologically derived material becomes bio-based material, which is defined as material made from substances extracted from living tissues. With the growing environmental concern, this area of materials is gaining more interest everyday. These materials are usually non-toxic and biodegradable. Included in the classification are polyesters and polythioesters from bacterial fermentation, monosaccharides and oligosaccharides from chitin, polyurethanes from cashew nut shell liquid, etc. The properties of these materials can be manipulated by the functional groups incorporated into the polymeric backbone or as pendant side-chains. By adding functional groups such as thioesters, urethanes, and carbonates, the materials are given tunable thermal properties, durability, and hardness. These biomaterials are found in every aspect of life from cushions to artificial organs and tissues.

Definition of "biomaterial" - material used for, or suitable for use in, prostheses that come in direct contact with living tissues. (Merriam-Webster Online Dictionary) What we mean by this term - material derived from biomass [by biological (enzymatic, fermentation, etc.) or conventional methods.]