The term 'doormat fiber' refers to the material coir, which is a natural fiber extracted from the husk of coconuts. Coir is used in the production of doormats and other products such as brushes, mattresses, and insulation. It is a strong and durable material that is resistant to salt water, making it ideal for use in coastal areas. Coir is also known for its ability to absorb moisture, making it an excellent choice for doormats.