A Biodegradable is Capable of decomposing under natural conditions.
Other /More definition:
A biodegradable is waste material composed primarily of naturally-occurring constituent parts, able to be broken down and absorbed into the ecosystem. Wood, for example, is biodegradable, for example, while plastics are not.
Other /More definition:
A Biodegradable is Material that can be broken down into simpler substances (elements and compounds) by Bacteria or other decomposers. Paper and most organic wastes such as animal manure are Biodegradable. See nonBiodegradable.