This acronym stands for medium density fiberboard, a wood-based substrate used for furniture, cabinetry, shelving, architectural paneling, and trims. Made up of fine hardwood and/or soft fibers that blend in multiple directions, many types of MDF are comprised of 100% recycled and/or recovered wood material. It is resilient, long-lasting, relatively lightweight, and dimensionally stable, all of which allows for great design flexibility.